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Journal of Chromatography A, 1216 (2009) 7964–7976

Contents lists available at ScienceDirect

Journal of Chromatography A

journa l homepage: www.e lsev ier .com/ locate /chroma

eview

esidue analysis: Future trends from a historical perspective

.F. De Brabander a,∗, H. Noppe a, K. Verheyden a, J. Vanden Bussche a, K. Wille a, L. Okerman a,. Vanhaecke a, W. Reybroeck b, S. Ooghe b, S. Croubels c

Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Laboratory of Chemical Analysis,esearch group Veterinary Public Health and Zoonoses, Salisburylaan 133, B-9820 Merelbeke, xxxx BelgiumInstitute for Agricultural and Fisheries Research, Technology and Food Unit, Brusselsesteenweg 370, B-9090 Melle, xxxxBelgiumGhent University, Faculty of Veterinary Medicine, Department of Pharmacology, Toxicology and Biochemistry, Salisburylaan 133, B-9820 Merelbeke, xxxxBelgium

r t i c l e i n f o

rticle history:vailable online 21 February 2009

a b s t r a c t

A residue is a trace (�g kg−1, ng kg−1) of a substance, present in a matrix. Residue analysis is a relativelyyoung discipline and a very broad area, including banned (A) substances as well as registered veterinary

eywords:esiduesanned substanceseterinary medicinal products

medicinal products (B substances). The objective of this manuscript is to review future trends in theanalysis of residues of veterinary drugs in meat producing animals out of historical perspectives. Theanalysis of residues in meat producing animals has known a tremendous evolution during the past 35–40years. In the future, it can be foreseen that this evolution will proceed in the direction of the use of moreand more sophisticated and expensive machines. These apparatus, and the necessary human resources fortheir use, will only be affordable for laboratories with sufficient financial resources and having guarantee

for a sufficient throughput of samples.

© 2009 Elsevier B.V. All rights reserved.

ontents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79652. Analysis of group A substances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7966

2.1. The analysis of residues of EGAs (groups A1, A3, A4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79662.2. Thyreostatic drugs analysis (group A2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79672.3. Beta adrenergic agonists (group A5) and their analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79672.4. Annex IV substances (group A6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79682.5. The analysis of corticosteroids (group B2f) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79682.6. Bovine somatotropins and their analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7968

3. Analysis of group B substances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79683.1. Anti-infectious agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7969

3.1.1. Rapid screening tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79703.1.2. Confirmatory methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7970

3.2. Other veterinary drugs (group B2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79713.2.1. Anthelmintics (group B2a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79713.2.2. Anticoccidials (group B2b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79723.2.3. Carbamates and pyrethroids (group B2c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79723.2.4. Sedatives (group B2d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79723.2.5. NSAIDs (group B2e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7972

3.2.6. Other pharmacologically active substances (B2f) . . . . . . . .

3.3. Other substances and environmental contaminants (B3) . . . . . . . . . .4. Conclusions and future trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

∗ Corresponding author. Tel.: +32 9 264 74 62; fax: +32 9 264 74 92.E-mail address: Hubert.DeBrabander@UGent.be (H.F. De Brabander).

021-9673/$ – see front matter © 2009 Elsevier B.V. All rights reserved.oi:10.1016/j.chroma.2009.02.027

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7972. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7972

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7972

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7973. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7973

omatogr. A 1216 (2009) 7964–7976 7965

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H.F. De Brabander et al. / J. Chr

. Introduction

Historically seen, the analysis of residues of chemicals in foodsf animal origin is a relatively young discipline. In the BENELUXBelgium, The Netherlands and Luxemburg) one can say thatesidue analysis started in the late 1960s or the early 1970s. TheENELUX SP/Lab/h documents illustrate the cooperation in residuenalysis between several laboratories in The Netherlands and Bel-ium: the first traceable document dates from 1978 [1]. In mosturopean countries research on residues and the application inegulatory control on slaughter animals started later. A residue

ay be defined as a trace of a substance, present in a matrix (e.g.eat, urine, etc.) after some kind of administration (e.g. within

he framework of veterinary practice or illegal use) to an animal.n all cases, concentration levels in the ppb concentration range�g kg−1) or even lower (ppt; ng kg−1) have to be detected. Theubstances involved may be divided into two major classes accord-ng to council directive 96/23/EC [2]: group A and B substances.roup A involves the growth promoters abused in animal fatten-

ng and the “no maximum residue limit (MRL)” substances anday be subdivided into four major groups: anabolics or anabolic

teroids, thyreostats, beta-agonists or repartitioning agents andnnex IV substances. Corticosteroids (CoST) may also be abuseds growth promoters, although they belong to the class of vet-rinary drugs. In this article CoST are treated as A substances.roup B contains the veterinary drugs or veterinary medicinal prod-cts (VMPs): antibacterial substances, other VMPs as anthelmintics,occidiostats, carbamates and pyrethroids, sedatives, non-steroidalnti-inflammatory drugs (NSAIDs) and other pharmacologicallyctive substances. The analytical requirements for both groups areifferent.

For banned (A) substances the emphasis lays on the identifi-ation of the substances in a large number of matrices (e.g. meat,rine, hair) in a concentration as low as possible (zero tolerancerinciple). In this case, at first qualitative multi-residue meth-ds have to be developed and secondly quantificative methods.ecent developments in the use and abuse of growth promoters areeviewed [3]. For B substances having a MRL, methods for the quan-itative determination of the substances in edible matrices only (e.g.

eat, liver) have to be worked out. In most cases the MRLs of Bubstances are a magnitude 10–100 times higher than the recom-ended concentrations (minimum required performance levels;RPLs) of the A substances [4]. A recent review on the analytical

trategies for residue analysis of veterinary drugs and growth-romoting agents in food-producing animals was published in this

ournal [5].In the early 70s thin layer chromatography (TLC) was the method

f choice for the qualitative detection of banned substances (thyre-stats and certain anabolics at that time). The reasons thereforeere the specificity, the simplicity of development in two dimen-

ions and the possibility of reaching low limits of detection for ancceptable budget (often using fluorescence detection). The onlylternative with acceptable limits of detection – at that moment –as gas chromatography with electron capture detection (GC-ECD).igh-performance liquid chromatography (HPLC) with UV detec-

ion was introduced in the middle 70s, but the first instrumentsere expensive and not robust. UV detection does also not match

he specificity and limits of detection needed for A substances. Flu-rescence detectors were only introduced later. However, for theuantitative determination of B substances UV detection and post-olumn derivatisation was often used. During the 90s more and

ore affordable gas chromatography–mass spectrometry (GC–MS)

pparatus appeared on the market and the transition from TLC (andPLC) to GC–MS methods was ongoing. Somewhat later on (endf the 90s), LC–MSn belonged more and more to the mandatorytandard equipment of a residue laboratory. In Fig. 1 the evolu-

Fig. 1. Evolution of methods used in residue analysis in function of time.

tion of methods used in residue analysis in function of time ispresented.

Next to the improving detection capability of the instrumenta-tion also the clean-up of the samples prior to instrumental analysishas undergone an evolution in function of time. As a general rule theresults of the instrumental technique are correlated strongly withthe efficacy of the clean-up. While in the 70s only solvent extractionand homemade columns (e.g. Silicagel, AlO) were used for clean-up,solid-phase extraction (SPE; 80s), immuno affinity chromatogra-phy (IAC; 90s) and molecular imprinted polymers (MIPs; end 90s)took over the job. HPLC fractionation, also often used, results inseveral purified fractions each containing a limited number ofanalytes and matrix components. In that aspect comprehensive(two-dimensional) GC or LC prior to MS may be important in thefuture.

Next to clean-up and analysis, the knowledge of the metabolismof A and B substances is important. Often not the parent (original)substances have to be detected but also one or more metabo-lites, depending upon the matrix analysed. Animal experiments areneeded for those purposes but also some alternatives have beendescribed [6,7].

In this review literature is retrieved from different sources overa period of ca. 35 years. Next to the traditional peer-reviewed a1journals in which residue chemists publish also the proceedings ofthe two main Benelux conferences in the field: “Euroresidue” (sixeditions) and the international conference on hormone and veteri-nary drug residue analysis “the Ghent conference” (seven editions)were used.

The analytical method and its performance must always be seenin the light of the interpretation of the analytical result. Food inspec-tion services are interested mainly (only?) in YES/NO answers:has this animal been treated illegally? Is the concentration of theresidue higher than a certain value (MRL), etc.? In fact all questionsmay be resumed to one major question: is the sample compliant oris the law violated? When the answer to that last question is YES,

legal actions have to be taken. Therefore the analytical results mustbe accurate “beyond any reasonable doubt”.

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966 H.F. De Brabander et al. / J. Chr

. Analysis of group A substances

Group A or banned substances comprise the growth promot-rs abused in animal fattening and may be subdivided into fourajor groups: Anabolics or anabolic steroids (group A1, A3, A4;

.g. diethylstilbestrol, nortestosterone), Thyreostats (group A2; e.g.ethylthiouracil), Beta-agonists or repartitioning agents (group A5;

.g. clenbuterol) and Annex IV substances (e.g. chloramphenicol).orticosteroids (group B2f; e.g. dexamethasone) may also be abused

n animal fattening, but belong to the class of veterinary drugsgroup B2f). A review on the past, present and future of mass spec-rometry in the analysis of banned substances in meat producingnimals has been published earlier [8].

The distinction between natural (endogenous) substances orhose suspected or proved to be endogenous (semi-endogenousn some species and under certain circumstances) and exogenousubstances, is an emerging challenge for the future. Examplesre nortestosterone, boldenone and thiouracil [9–11]. Examples oftructural formulas of A substances are given in Fig. 2.

.1. The analysis of residues of EGAs (groups A1, A3, A4)

Steroid hormones are steroids which act as hormones. Thisroup of compounds contains both the sex hormones, estrogens,estagens and androgens (EGAs) as well as the corticosteroids.lthough the use of this large group of compounds for animal fat-

ening purposes has been described since the early 1950s it haseen prohibited in the European Union nowadays [3,5,12,13].

As reviewed by Stolker and Brinkman [5], De Brabander et al.

8] and Noppe et al. [13] endogenous estrogens or C18-steroidsestrone, estradiol, estriol) and their semi-synthetic analogues (e.g.stradiol-3-benzoate) are less orally active in comparison with syn-hetic estrogens (e.g. ethinylestradiol, the synthetic counterpart ofstradiol). Stilbenes (e.g. diethylstilbestrol, dienestrol, hexestrol)

Fig. 2. Examples of structural f

gr. A 1216 (2009) 7964–7976

and zeranol are xenobiotic non-steroidal compounds mimickingestrogenic effects through structural similarities with estradiol[12]. For animal fattening purposes, gestagens (C21-steroids)are frequently employed as esters (e.g. melengestrol-acetateor medroxyprogesterone-acetate), either alone or in combina-tion with estrogens [12]. Well-known examples of androgensused in animal fattening are 19-nortestosterone (also known asnandrolone), 17�-methyltestosterone, boldenone and trenbolone.Besides these, a lot of other analogues have been synthesized aswell (e.g. stanozolol, 4-chlortestosterone, norethandrolone and flu-oxymesterone) [12]. Finally, there are also the so-called “designerdrugs”, all kind of new drugs regularly introduced in the blackmarket and on the Internet. In most cases, these substances arevariations of ‘old’ structures. Well-known examples of “designerdrugs” with a steroid structure are norbolethone, tetrahydrogestri-none (THG) and desoxy-methyltestosterone (DMT) [13–17].

To monitor illegal use of steroid hormones, urine and manure,which are available prior to slaughtering and which contain thehighest hormone concentrations, are mostly selected. After slaugh-tering, organ tissue (e.g. liver, kidney), hair, fat and meat can be usedfor monitoring [5].

In recent years, concerns have risen about the presence of steroidhormones in edible matrices, covering a wide range of physicaltypes of matrix, from muscle and organ tissue (liver and kidney) tofat, milk and the non-edible matrices urine, faeces and hair. Conse-quently, there was a need for continuous development of improvedmulti-residue, multi-matrix and multi-technique analytical meth-ods [5,13].

Conventionally, solid samples (e.g. muscle, fat, kidney, liver,

faeces) are extracted for steroid hormones with organic sol-vents (mostly methanol) [5,12,14,18–21] based on liquid–solidpartition, normally preceded by grinding and/or freeze dry-ing and homogenizing, followed by a multi-step clean-upusing liquid–liquid extraction (LLE) and/or SPE or liquid–solid

ormulas of A substances.

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xtraction (LSE) [12,18,21–23]. Most of the described methodsre based on the determination of free steroids involving hydrol-sis using Helix pomatia juice, containing �-glucuronidase andryl sulphatase of which the usefulness has however been dis-ussed [12,18,20,21,23–25]. Although many advanced extractionnd purification techniques for steroid hormones from matricesf all kinds of origin have been described (e.g. accelerated solventxtraction (ASE), supercritical fluid extraction (SFE), solid-phaseicroextraction (SPME), microwave-assisted extraction (MAE),IPs, restricted access media (RAM) and size exclusion chromatog-

aphy (SEC)), it is surprising that only few applications in the fieldf residue analysis of steroid hormones in matrices of animal originre described [13,26–29].

Initial screening of matrices of animal origin was performedsing immunological techniques like radio immunoassay (RIA)nd enzyme-linked immunosorbent assay (ELISA) [30–36]. Latern, confirmation of steroid in suspected samples was car-ied out using chromatographic separation methods like TLC37–43].

Nowadays, the determination of steroid hormones within theramework of residue analysis is dominated by the coupling of ahromatographic separation method (GC or LC) to a sensitive andpecific detection system such as ion trap of quadrupole (QqQ)S. As reviewed by Noppe et al. [13] gas chromatography cou-

led to single or multiple MS is the common used technique foresidues of steroid hormones [12,18–20,22,24,44,45]. This usuallyfter silylation of the compounds (e.g. using MSTFA) due to theiroor thermal stability and volatility. Since the introduction of thetmospheric pressure interfaces (APIs), such as electrospray (ESI)nd atmospheric pressure chemical ionization (APCI) and the pos-ibility to couple LC to ion trap or quadrupole MS, LC–MS-(MS) hasained in popularity. Although many LC–MS methods have beeneveloped for the analysis of steroids or steroid-like substances innvironmental samples [46–51], the applications for residue anal-sis are rather limited [21,23,29,52]. Most of the reported methodsre using GC–MSn, however in recent years multi-analyte LC–MSn

ethods are published for the determination of steroids in urineithin the framework of doping analysis or veterinary control

53–64].

.2. Thyreostatic drugs analysis (group A2)

Thyreostatic drugs (TS) are a complex group of substances thatnterfere with the metabolism of the thyroid gland, resulting in aecreased production of its hormones triiodothyronine (T3) andhyroxine (T4) [65]. Administration of TS to livestock causes aeight gain by an increased filling of the gastrointestinal tract

s well as the retention of water in edible tissues [66,67]. Sub-equently, the meat derived from the treated animals is of loweruality. Moreover, these edible animal tissues (muscles, organs)ontain TS residues, which represent a potential human healthisk due to the teratogenic and carcinogenic properties of theseesidues [68,69]. For these particular reasons, the use of TS, for ani-

al fattening purposes is banned in the European Union (1981)70].

Thyreostats can be divided in two main groups, respectivelyhe xenobiotic and the natural occurring sulfur compounds (e.g.hiocyanates and oxazolidine-2-thiones) [3]. These are polar,mphoteric thioamides, characterized by a low molecular weight.

Because of the increasing production of livestock, the illegal usef growth-promoting agents remains an important problem. An

dequate residue control plan, to monitor this illegal treatment isn absolute requirement. Therefore, analytical approaches need toe developed for the detection of TS residues in different matricesf animal origin (e.g. urine, faeces, muscle, organs, animal feed andair). Recently, an extensive review of the analysis of thyreostats

gr. A 1216 (2009) 7964–7976 7967

in biological matrices has been published by Vanden Bussche et al.[71].

In former years, the symptoms of the thyroid disorder hypothy-roidism, caused by the administration of TS, were used as anindication of possible TS abuse. Over the last years, chromato-graphic separation methods (GC or LC), coupled to sensitive andspecific detection techniques such as mass spectrometry [72–78]have dominated the residue analysis. Nowadays, LC coupled toMS and more specific, coupled to multiple MS, has gained inpopularity [74,76–78]. The conventional residue control planshowever, only screen for the xenobiotic TS: 4(6)-R-2-thiouracil(R = hydrogen, methyl, propyl, phenyl), tapazole (TAP), and 2-mercaptobenzimidazole (MBI).

In 2005 work has been carried out in order to increase theperformance of TS detection by focusing on derivatisation priorto GC–MS/MS or LC–MS/MS analysis [74,77]. Implementing suchimproved detection method, resulted in an occasionally detectionof thiouracil (TU), below 10 �g l−1, in urine of cattle [11]. Therefore,the erroneous indication of possible illegal use of TU may be sus-pected and the question of the possible semi-endogenous status ofTU arises.

Within the framework of TS residue control, the possible nat-ural occurrence of TU is of uttermost importance. A more carefulinterpretation is needed for samples suspected of being “non-compliant” with regard to thiouracil abuse. For discriminationbetween urine containing thiouracil of a natural origin or as a con-sequence of an abuse, one could for example rely, in the future onspecific phase I or II metabolites.

2.3. Beta adrenergic agonists (group A5) and their analysis

Beta adrenergic agonists (BAA) are a relatively new class of illegalgrowth promoters (since ca. 1986). BAAs decrease the fat contentof the carcass in favour of a higher percentage of muscle. In the EUthese substances are banned and MRPL values for most of thesesubstances are in preparation [3,8]. In other countries like the USA,Mexico and South Africa some BAAs (as zilpaterol) are licensed foranimal fattening [79–81].

Historically (and practically) clenbuterol is the most importantBAA. The first methods for clenbuterol were based on immunoas-says or HPLC using post-column derivatisation [82]. GC–MS hasalso been widely used and different derivatisation techniques havebeen proposed [83–85]. New reliable and fast-screening ELISAand radioimmunoassays have been developed [86,87] and sur-face plasmon resonance (SPR) biosensor veterinary drug tests canbe applied for the analysis of these compounds as well [88]. Inaddition, capillary zone electrophoresis and miniaturized capillaryelectrophoresis have been used for the separation and detectionof BAAs [89,90]. Despite the availability of many different types oftechniques, LC–MS has been shown to be the method of choice forthe control of these substances [91–95] although emerging tech-nologies such as ultra-performance liquid chromatography (UPLC)with fast-switching MS/MS and quadrupole time of flight (Q-TOF)MS provide further simplification and improvement to their analy-sis [94,95]. A phenomenon which however affects many aspects ofthe MS method performance, is ion suppression [96]. The cause ofion suppression is a change in the spray droplet solution propertiesarising from the presence of co-eluting non-volatile or less-volatilesolutes. Polar compounds such as BAAs seem to be particularly sus-ceptible to ion suppression. Therefore, one can observe a tendency

to improve sample preparation before LC–MS analysis in order tominimize these kinds of problems. The use of MIPs for the sampleclean-up of beta-agonists has been investigated, demonstrating theimportance of a proper clean-up prior to sophisticated hyphenatedtechniques as LC–MS [84,97,98].

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968 H.F. De Brabander et al. / J. Chr

.4. Annex IV substances (group A6)

For substances listed in Annex IV of Council regulation377/90/EEC no MRL can be set on safety grounds. Annex IV sub-tances may not be administered to food-producing animals. Theost important Annex IV substances are chloramphenicol (CAP)

nd the nitrofurans, mainly at import of poultry and aquacultureroducts from third countries. CAP is a broad-spectrum antimicro-ial substance produced by the growth of certain strains of the soilacterium Streptomyces venezuelae, but now mainly prepared syn-hetically. For chloramphenicol a large number of methods haveeen described (4884 hits in the web of science). In our laboratorycreening and confirmation of CAP in shrimp tissue was performedy a combination of ELISA with GC–MS2 and LC–MS2 [99]. Usinghis method the national Belgian MRPL of 0.1 �g kg−1 (lower thanhe EU MRPL = 0.3 �g kg−1) was easily fulfilled. This is an examplef the low limits of detection which could be obtained if a methodould be focused on only one well-known substance (CCß of theethod <0.1 �g kg−1).

Nitrofurans are also banned substances with an MRPL1 �g kg−1). For nitrofurans especially the work of “FoodBRAND”Bound Residues And Nitrofuran Detection – must be mentioned:evelopment of rapid multi-residue screening tests and definitiveulti-residue reference methods for tissue-bound residues of the

itrofurans. This is an example where not the parent drug but arotein bound remnant of the substances has to be detected. Manyethods were described allowing the detection of the tissue-bound

esidue of nitrofurans [100–106] to monitor the EU ban on the usef nitrofurans in animal production effectively.

.5. The analysis of corticosteroids (group B2f)

Corticosteroids are frequently used drugs in human and veteri-ary medicine, often in combination with antimicrobial drugs or-agonists. Well-known examples are dexamethasone, betametha-

one and prednisolone. Among the more recent compounds foundn preparations, clobetasolpropionate and beclomethasonedipropi-nate can be mentioned [3,13,107].

The legal utilisation of some CoST hormones in veterinaryedicine is strictly regulated, with withdrawal periods between

reatment and slaughtering. These substances have also been usedllegally as growth promoters in cattle. Indeed, low concentrationsf CoST are known to increase weight gain, reduce feed conversionatio, and exert a synergetic effect with other substances [108,109].o, the difference between legal and illegal use of CoST is sometimesmall. During the 80s and early 90s, the main detection methodssed for CoST were radioimmunology [110], fluorimetry (after HPLCr TLC) [111,112] or liquid chromatography with UV detection [113].C–MS with electron impact (EI) was the first mass spectromet-

ic technique being applied for those compounds [114–118]. Theost currently used techniques remain chemical oxidation (elim-

nation of the polar C17 side chain) followed by negative chemicalonization (NCI), or classical silylation followed by positive electronmpact [114–118].

At the contrary, LC allows direct measurement of CoST. The sen-itivity question is probably the less critical issue, considering theery high performances of the more recent mass filters (last gen-ration of 3D ion trap or triple quadrupoles, new systems like 2Don trap or OrbitrapTM, etc.). With regard to mass spectrometricpproaches for the detection of new compounds, the combined usef LC–API-MSn and GC–EI-MSn techniques is certainly the key to

uccess. Indeed, the LC-based systems authorize very quick andfficient comparative analysis, permitting to reveal the presencef potential analytes of interest, while the GC-based system leadso more abundant structural data for unambiguous identification.owadays many methods for the fast and unambiguous determi-

gr. A 1216 (2009) 7964–7976

nation of CoST in different matrices of animal origin are developed[119–125]. Touber et al. [126] described a multi-detection methodusing UPLC coupled to TOF MS for the determination of 40 corticos-teroids and �-agonists in calf urine but so far no further applicationsare described for this very promising technique in the field ofresidue analysis.

2.6. Bovine somatotropins and their analysis

Somatotropins (STs), also called growth hormones (GHs), areproteinaceous hormones, naturally produced by the anterior pitu-itary gland. Both direct and indirect effects on somatic andmetabolic processes such as growth, immune response, repro-duction and lactation in mammals are known to be exertedby somatotropins [127–129]. In particular bovine somatotropins(BSTs), naturally produced by cattle, have been known to increasemilk yield [128,129]. And this characteristic has led to theproduction of synthetical bovine somatotropins, referred to asrecombinant bovine somatotropins (rBSTs), identical in activitybut slightly differing in chemical structure from the pituitarysomatotropins [128,130]. Several studies reported the efficacyof rBST-administration to lactating cows in enhancing milkyield [130–132] and even in improving growth performances[130,132,133].

Although legally used in the USA and some other countries, rBSTsare banned in Canada, Australia, New Zealand and the EuropeanUnion (EU) based on concerns over potential effects on animal andhuman health [127,129,134]. Nevertheless, their illegal use for milkproduction and growth promotion in the EU cannot be neglected.

Despite the ban on these hormones in some countries, theredoes not exist so far a standard analytical method for their directdetection neither in milk, plasma or other tissues [135], nor ininjection preparations [128]. Formerly used analytical methodsto determine BSTs consisted of immunoassays such as radioim-munoassays (RIAs) and enzyme-linked immunoassays (ELISAs)[136,137]. Unfortunately, these assays appeared unable to dis-tinguish between endogenous and recombinant somatotropine[127,130]. To overcome this drawback, research is recently focussingon the development of more specific and more sensitive methods.

Extraction and purification of BSTs from different biologi-cal matrices holds gel permeation chromatography (GPC) [127],immunoaffinity chromatography (IAC) [127,130] and 2D elec-trophoresis [129]. Accurate detection techniques, recently reported,are LC–MSn [127–130,138] and liquid chromatography coupled tohigh-resolution mass spectrometry (LC–HRMS) [135]. These meth-ods do allow unambiguous detection of somatotropin treated cowsbut agreement on a single standard method for residue controlpurposes in the EU remains a challenge.

3. Analysis of group B substances

Group B involves the VMPs for which maximum residue limitshave been fixed. Before a VMP intended for use in food-producinganimals can be authorized in the EU, in accordance with Coun-cil Directive 81/851/EEC, all pharmacologically active substancescontained in the product have to undergo a safety and residue eval-uation according to the provisions laid down in Council RegulationNo. 2377/90/EEC and have to be included in Annex I, II or III ofthis Regulation. The safety and residue evaluation is carried out bythe Committee for Veterinary Medicinal Products (CVMP) of the

European Agency for the Evaluation of Medicinal Products (EMEA)in London, and is supported by safety and residue experts, uponreceipt of a valid application for the establishment of MRLs. Forsubstances in Annex I definitive MRLs have been set; for substancesin Annex III they are provisional and still to be finalized. Where, fol-

H.F. De Brabander et al. / J. Chromatogr. A 1216 (2009) 7964–7976 7969

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owing the evaluation, it appears that it is not necessary for therotection of public health to establish MRLs, such substance is

ncluded in Annex II. Any substance not included in Annex I, II, orII by 31 December 1999 resulted in the marketing authorization ofroducts containing this substance being withdrawn.

A safety and residue evaluation may also result in the rec-mmendation to include a substance in Annex IV of Regulation377/90/EEC, which means that the substance is prohibited fromse in veterinary medicinal products for food-producing animals.

The MRLs can be found in the European Public MRL Assessmenteports (EPMARs), published on the EMEA website.

Examples of structural formulas of B substances are given inig. 3.

Methods for surveillance testing of VMPs may be subdividednto screening methods and confirmatory methods. Screening meth-ds are tools that are used to detect the presence of an analyter class of analytes at the level of interest. These methods havehe capacity for high sample throughput and are used to siftarge numbers of samples for potential non-compliant (or posi-ive) results. They are specially designed to avoid false compliant

esults. Confirmatory methods are methods that provide full oromplementary information enabling the analyte to be identifiednequivocally, and if necessary quantified, at the level of interest.onfirmatory methods must fulfil the criteria listed in Commissionecision 2002/657/EC and must be based on molecular spec-

ormulas of B substances.

trometry providing direct information concerning the molecularstructure of the analyte under examination, such as GC–MS andLC–MS.

Methods of analysis of antimicrobials may also be groupedinto three classes on the basis of the principle used: microbi-ological, immunochemical, or physico-chemical. Microbiologicalmethods for detection of antimicrobial residues are fast screeningtests. Immunochemical methods fall into two groups, immunoas-say and immunoaffinity chromatography (IAC). Immunoassays canbe rapid, selective, and sensitive and have proved of considerableutility in some areas of residue analysis. Physico-chemical methodsare based on chromatographic purification of residues followed byspectroscopic quantification such as UV, fluorescence or MS detec-tion.

3.1. Anti-infectious agents

The term antibiotics is reserved for agents derived from liv-ing organisms, or for synthetic or semi-synthetic analogues ofsuch compounds. The antibiotics used in veterinary medicine

fall into seven classes: �-lactams; tetracyclines; macrolides,lincosamides and pleuromutulins; aminoglycosides and aminocy-clitols; amphenicols; peptides and ionophores. Strictly speaking,sulfonamides, nitroimidazoles, nitrofurans and quinolones are notantibiotics, being synthetic and are therefore called chemothera-

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eutics. Nevertheless, in this review both groups are included inhe class of anti-infectious agents.

.1.1. Rapid screening testsUp till now, screening for antimicrobials has been done with

icrobiological inhibition tests, and it is not probable that theseests will be replaced by other techniques in the near future. Indeed,uch tests are cheap and permit to analyse a large number of sam-les in a short time, providing that no extraction is included in therocedure.

Microbiological screening relies on the common property of allntibacterials: they inhibit growth of microorganisms. Inhibitionests have been considered unspecific, but the microorganisms useds test bacteria are of course not equally sensitive to all antibiotics.s a consequence, they detect some substances better than others.

In the past, many efforts have been done to develop a simpleethod that detects a large range of antibiotics. Inhibitor-positiveilk rarely contains other antibiotics than beta-lactam: thus theost common methods use Geobacillus stearothermophilus, which

s very sensitive to this antibiotic family. Several commercial testits contain this strain and absence of inhibiting substances isemonstrated by change of the colour of the indicator within a fewours after incubation [139].

Such tests are less well suited for slaughter animals, becausether antibiotic families, and especially tetracyclines, are most oftenound in meat. In the past, only plate tests have been used for animalissues, where the inhibiting substance produces a zone withoutrowth around the tissue or tissue fluid. Kidney has been consid-red as a good target organ, because kidney tissue, and especiallyhe fluid in the kidney pelvis, contains high concentrations of mostntibacterials. It is also possible to analyse muscle meat, but in thatase three or four plates are necessary to obtain lower limits ofetection [140].

Combinations of different test bacteria, each in an optimaledium, are now considered as the best tool to detect a large

ange of antibiotics up to the MRL levels in animal tissues. Therigin of the strains can be found in the cited literature. Opti-al or very good detection capabilities of beta-lactam antibiotics

nd cephalosporins are obtained with G. stearothermophilus [141],ocuria rhizophila (formerly Sarcina lutea and Micrococcus luteus)141–143] and Bacillus subtilis [141], while macrolides are bestetected with K. rhizophila [141]. Low LODs have been described

or tetracyclines with Bacillus cereus [144], and for quinolones withscherichia coli [141,145] and Yersinia ruckeri [146]. Sulfonamides areetected with G. stearothermophilus [142] and with Bacillus pumilus143]. B. subtilis spores are added to media intended for aminoglyco-ides [142,143]. The pattern of inhibition indicates which antibioticamily or families should be searched for and reduces the numberf expensive confirmation methods [141–143,147].

To avoid the long incubation period inherent to microbiologicalnhibitor tests, enzymatic, receptor and immunological tests wereeveloped for a rapid screening of foodstuffs of animal origin onhe presence of antimicrobials.

The dairy industry has always been interested in rapid tests tocreen the incoming milk on residues of beta-lactam antibiotics inrder to prevent technological problems when producing cheeser yoghurt [148]. The first fast test developed for that aim was theenzym test, an enzymatic (carboxypeptidase) colorimetric test,iving a result in 20 min [149]. End of the 80s, early 90s, severalcreening tests with a total test time below 10 min (receptor testsNAP, Charm MRL Beta-lactam Test (ROSA) and �eta-s.t.a.r. and

mmunoassays Lactek and Parallux), became commercially avail-ble for monitoring of raw milk on beta-lactams [139,150–156].ore recently, some rapid tests (Charm MRL-3 [157] and �eta-

.t.a.r. 1+1 [158]) were adapted to give a test result within 3 min,llowing screening of milk at the farm before collection. Also rapid

gr. A 1216 (2009) 7964–7976

tests for the detection of tetracyclines (SNAP Tetracycline TestKit, TetraSensor Milk, Charm Tetracyclines (ROSA)), sulfamethazine(SNAP Sulfamethazine Test Kit, Charm SMZ), sulfadimethoxine andsulfamethazine (Charm SDSM), gentamicin (SNAP Gentamicin TestKit), enrofloxacin (Charm ROSA Enrofloxacin) or for a simulta-neous detection of beta-lactams and tetracyclines (TwinSensorMilk [159,160], Charm ROSA MRLBLTET-3 [161] and SNAP Duo) arepresent on the market. Parallux Milk Residue Testing System detectsall six major beta-lactams, tetracyclines, spectinomycin, neomycin,streptomycin, spiramycin, sulfa drugs and quinolones in one testin 4 min. In the near future dipstick tests for the rapid screening onwhole antimicrobial families like sulfonamides and quinolones willbecome available.

The gamma of real rapid tests for food matrices different frommilk is much smaller. When performing a special extraction pro-cedure SNAP, Parallux and �eta-s.t.a.r. reagents could be used fortesting of tissue (meat) on beta-lactam residues. Tetracyclines canbe screened in 13 min in tissue, kidney, liver and eggs with theTetraSensor Tissue at two different sensitivity levels [144]. TheTetraSensor Honey sensitively detects the four most importanttetracyclines in honey in 30 min without special equipment, mak-ing analysis at the production site possible [162]. Another on-sitehoney test is the CAP Residue Rapid Inspection Device (40 min) forthe detection of chloramphenicol.

For the detection of residues of the most important families ofantimicrobials (beta-lactams, tetracyclines, sulfonamides, amino-glycosides, macrolides and lincosamides) in different food matrices(milk, tissue, eggs and honey) Charm II reagents could be used [163].The sample preparation is depending on the matrix; the assay itselftakes about 30 min. Also ELISA kits are often used for the detectionof residues of some antibiotic compounds or families in differentmatrices; however with a test time around 90 min they cannot beconsidered as rapid [164,165]. An alternative is a biosensor systembased on surface plasmon resonance (BiacoreTM) [88,166]. With thissystem, a high throughput and a rapid (around 5 min) multi-analytescreening in different matrices (milk, meat and honey) are possi-ble. However the instrument costs remain high and the range ofavailable biosensor kits rather limited.

Novel electrochemical and optical immunosensors [167], flowcytometric immunoassays [168] and biochip array technologyapplications [169] for residue analysis are presently under evalu-ation. Instead of using antibodies or receptors, new developmentsbased on aptamers, artificial oligonucleotides with a high affinityfor particular molecular targets, can be expected in the future [170].

3.1.2. Confirmatory methodsSince the establishment of international standards that ensure

human food safety and the harmonization of international tradein animal products, current chemical analysis techniques such asLC with photo-diode array detection, GC–MS and LC–MS are usedroutineously in analysis of residues of VMPs. However, the lack ofvolatility and thermal instability of many antibiotics makes LC–MSthe method of choice for their analysis. Several confirmatory meth-ods for each class of anti-infectious agents have been published, asillustrated below.

The �-lactam antibiotics comprise several classes of compounds,among which penicillins and cephalosporins are the most impor-tant. Multi-residue analysis methods for �-lactams and majormetabolites in meat and milk [171–175] have been described. Onlyrecently, quantitative methods using LC–MS/MS for analysis of the�-lactamase inhibitor clavulanic acid in tissues are available [176].

Most sulfonamide formulations are supplied as combinationproducts having two main components, a sulfonamide and thesynthetic diaminopyrimidine, trimethoprim. These combinationsare believed to act synergistically on specific targets in bacterialDNA synthesis. Multi-residue methods for sulfonamides and/or

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rimethoprim have been published for analysis of milk and eggs177,178], meat and infant foods [179–182] and honey [183,184].

The major representatives of the tetracycline group availablen the EU for treating food-producing animals are tetracycline,xytetracyline, chlortetracycline, and doxycycline. Multi-residueethods have been published which quantify the marker residue

i.e. sum of parent compound and its 4-epimer) in tissues [185–191]nd cheese [192].

Quinolone and fluoroquinolone chemotherapeutics are a groupf highly potent, synthetic antibiotic compounds, derived from 3-uinolonecarboxylic acid. Multi-residue methods using LC–MS/MSave been published for detection of quinolones in animal tissues193–199], milk [199,200], honey [201], shrimp [202] and fish [203].C-FLD (fluorescence detection) methods include determination inggs [204].

Macrolide antibiotics constitute a very important class ofntibacterial compounds widely used in veterinary medicine toreat respiratory diseases or as feed additives to promote growth.hese antibiotics consist of 14-, 16- or 17-membered macrocyclic

actones to which sugar moieties, including amino and deoxy sug-rs, are attached. Confirmatory methods using LC–MS/MS haveeen published for residues of macrolides and lincosamides in ani-al tissues [205–207].

The aminoglycoside and aminocyclitol group of antibioticsncludes bactericidal compounds elaborated by Streptomyces (in

hich case they are named -mycins) and Micromonospora species-micins). Confirmatory methods using LC–MS/MS have been pub-ished for the determination of aminoglycoside residues in animalissues and milk [208–210].

Only a few methods for determination of residues of ampheni-ols with a MRL, i.e. thiamphenicol and florfenicol, including thearker residue florfenicol amine are available for farmed aquatic

pecies [211,212].The main antibacterials among the peptides used in veterinary

edicine in Europe are bacitracin and polymyxin E or colistin. Aethod for simultaneous determination of bacitracin and colistin

n food samples has been described [213]. In the EU, the use ofvoparcin and ardacin as growth promoters in animal feed has beenanned since 1997, virginiamycin and zinc bacitracin since 1999 andambermycin and avilamycin since 2006.

The ionophores are polyether antibiotics that are used notgainst bacteria, but rather against coccidial (protozoa) infec-ions. Ionophore antibiotics form a coordinate bond with metalons and are able to transport cations across membranes against

concentration gradient. They include monensin, narasin, lasa-ocid, salinomycin, semduramycin and maduramicin. Since 2006,onophores are no longer allowed as growth promoter in animaleed. Methods for simultaneous determination of these compoundsn feeding stuffs [214] and eggs and broiler meat [215,216] have beenublished. Currently, MRLs for some of these compounds are beingstablished.

Besides single-class methods, multi-class methods usingC–MS/MS for the simultaneous determination of 130 veterinaryrugs and their metabolites in bovine, porcine and chicken mus-le [217]; for antibiotics from different classes in meat [218–221],oney [222,223], milk [224], eggs [225,226] and shrimp [227] haveeen developed.

Also reviews describing the state of the art in analytical strate-ies concerning multi-class as well as multi-residue analysis ofntibiotics for confirmatory analysis are available [5,228–236].

In the field of sample treatment, the combined use of liquid

xtraction and on- or off-line solid-phase extraction is still mostopular. Nevertheless, problems are still encountered with respecto the simultaneous extraction and pre-treatment of analytesith widely different polarities. Therefore, extraction methods

ave nowadays been developed which comply with the QuECh-

gr. A 1216 (2009) 7964–7976 7971

ERS methodology (quick, easy, cheap, effective, rugged and safe),consisting mainly of a simple liquid extraction step with filtrationwithout further sample clean-up [237]. Also generic approaches insample clean-up such as cation-exchange for use with acetonitrileextracts of foods, when analysing basic drug groups, are available[238]. The use of MIPs for solid-phase extraction of VMPs has alsobeen introduced recently. Only few methods are currently available[239–243], but MIPs may exhibit some potential for frequent use inthe future.

As mentioned before, liquid chromatography combined withtandem mass spectrometric detection – either triple-quadrupole orion-trap multi-stage – is the preferred technique in a large majorityof all VMP classes. As mentioned above, this also raises the prob-lem of ion suppression and matrix effect, which may be responsiblefor quantification errors. Assessment of the impact of ion suppres-sion and matrix effect is to the authors’ knowledge not required inCommission Decision 2002/657/EC, but it is strongly recommendedto study this during the validation of a quantitative method. Ingeneral, matrix-matched calibration curves with the use of an inter-nal standard should be used to achieve the best accuracy of themethod.

Nowadays, besides LC–MS/MS, also ultra-performance liquidchromatography/time-of-flight mass spectrometry (UPLC/TOFMS)is being used. Both techniques demonstrate good quantitative per-formance in terms of accuracy and precision. However, UPLC/TOFprovides ultimate and unequivocal confirmation of positive find-ings, and allows degradation product identification based onaccurate mass. The power of TOFMS has been demonstrated inthe analysis of 6 macrolides residues and degradation products ineggs, raw milk and honey [244], of more than 100 veterinary drugsin milk [245], urine [246] and meat matrices [247], of 8 tetracy-clines in honey [248], of quinolones in pig liver [249] and chickenmuscle [250] and of 3 N-oxides, quinoline N-oxide, carbadox andolaquindox [251,252].

Another problem encountered in multi-residue analysis is thespeed of analysis. This has been significantly improved with theintroduction of the UPLC technique. Recently, multi-residue meth-ods using UPLC have been published for determination of 18 VMPsin milk [237], 39 antibiotics (tetracyclines, quinolones, penicillins,sulfonamides and macrolides) in chicken muscle [253], 24 sul-fonamide residues in meat [254], egg and honey [255] and fortetracyclines and quinolones in pig tissues [256].

3.2. Other veterinary drugs (group B2)

This group contains the anthelmintics, anticoccidials, includ-ing nitroimidazoles, carbamates and pyrethroids, sedatives, NSAIDsand other pharmacologically active substances.

3.2.1. Anthelmintics (group B2a)An important aspect of efficient animal production is the effec-

tive control of helminthic infections that have long been recognizedas having major economic importance in the field of animal hus-bandry. Since the discovery of the first of the benzimidazole drugs,as many as 20 benzimidazoles and probenzimidazoles have beenintroduced. Reviews concerning multi-residue analysis of benzim-idazoles for confirmatory analysis are present [257–259].

Also salicylanilides such as closantel and imidazolthiazoles (i.e.levamisole) are used against endoparasites in animals. Only few

confirmatory methods with LC–MS for closantel [260–262] andlevamisole [263] are available.

Agents acting against endo- and ectoparasites include aver-mectins, for which multi-residue analysis methods have beenpublished for milk [264] and animal tissues [265–268].

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.2.2. Anticoccidials (group B2b)Coccidiostats are used for the treatment and prevention of

occidiosis, which is a contagious amoebic disease (Eimeria spp.)ffecting livestock, particularly poultry, throughout the world, inarticular in warm, humid environments.

Due to the intensive nature of the poultry industry, it is eco-omically essential to control this disease. Several compounds were

ntroduced since 1948, namely sulfonamides (1948), pyridinoles1968, e.g. meticlorpindol), 4-hydroxyquinolines (1970, e.g. deco-uinate), carbanilides (1955, e.g. nicarbazin), thiamine-analogues1960, e.g. amprolium), quinazolinones (1976, e.g. halofuginone),uanidine derivatives (1972, e.g. robenidine), ionophores (1971, e.g.onensin, salinomycin), the nitrofuran compound nifursol used

or treatment of black head disease in turkeys (1982) and tri-zines (1984, e.g. diclazuril). Another group of compounds that haveeen used are the nitroimidazoles. Nitrofurans, nitroimidazoles,eticlorpindol, nicarbazin and amprolium have however been pro-

ibited for use in the EU.Multi-residue methods have been published for analysis of coc-

idiostats in egg and muscle [269,270].

.2.3. Carbamates and pyrethroids (group B2c)The carbamate insecticides exist as esters of carbamic acid.

hese compounds are most soluble in organic solvents. The mode ofction of the carbamates is similar to that of the organophosphorusnsecticides, both are used against ectoparasites. The central nerveystem is the site of action of carbamates and they are responsibleor a carbamylation of the enzyme acetylcholinesterase.

Few confirmatory methods for analysis of carbamate pesticidesn biological samples are available [271–273].

The pyrethroid insecticides are typically esters of chrysanthemiccid, having a high degree of lipophilicity. The original compoundsn this series were the natural pyrethrins, which are isolated fromhe flowers of Chrysanthemum cinerariaefolium. Their analysis isampered by the presence of isomers, which are often included

n the marker residue of the MRL legislation. Most published meth-ds deal with the analysis of residues in plant materials and wateramples, however, for animal derived food products the literatures scarce [274,275].

.2.4. Sedatives (group B2d)Sedatives are often used in animal production, especially in pigs

hich are particularly sensitive to stress during handling and trans-ort to the abattoir. Stress leads to high mortality and meat of pooreruality (Pale, Soft, Exudative; PSE). Since the 1970s the use of seda-ives has become generalised to calm pigs down before transporto the slaughterhouse.

The use of certain substances (derived from phenothiazine: ace-,ropionyl- and chlorpromazine) is totally prohibited. Other sub-tances (butyrophenone: azaperone and �-blocker: carazolol) areegulated through the establishment of MRLs (100 and 25 mg kg−1,espectively). In the 90s a number of methods have been describedo detect sedatives in meat using LC with UV, electrochemical oruorescence detection [276–280]. A method for the detection ofesidues of five tranquillizers and one ß-blocker using a singleLISA plate was described [281]. Later on, mostly methods basedn LC–MS were developed [282–286] and applied in the regulatory

nspection on the abuse of sedatives.

.2.5. NSAIDs (group B2e)Hippocrates already recommended willow bark (containing sal-

cylates) to relieve the pain of childbirth and to reduce fever. Today, aumber of NSAIDs are used routinely in veterinary practice. In food-roducing animals the use of these drugs is restricted to registeredroducts for which a MRL is established. NSAIDs with a MRL arearprofen (bovine, equine), vedaprofen (equine), flunixin (bovine,

gr. A 1216 (2009) 7964–7976

porcine, equine), tolfenamic acid (bovine, porcine) and meloxicam(bovine, porcine, equine). Two NSAIDs do not have a MRL, namely,ketoprofen and salicylates. Literature data for analysis of NSAIDsindicate extraction and clean-up procedures for the determinationof one or two substances [287–302], with mass spectrometry asthe main detection technique. No literature data were found onmulti-residue methods in bovine muscle for these structurally dif-ferent compounds. In our laboratory a multi-residue method wasdeveloped for the determination of NSAIDs in bovine muscle [303].

3.2.6. Other pharmacologically active substances (B2f)The most important substances in this group are the corticos-

teroids (see Section 2.5).

3.3. Other substances and environmental contaminants (B3)

This group includes organochlorine compounds (e.g. PCBs),organophosphorus compounds, chemical elements, mycotoxins,dyes and some others and will not be reviewed in this manuscript.

4. Conclusions and future trends

The objective of this paper was to review future trends out of his-torical perspectives in the analysis of residues in meat producinganimals. This is a very broad area, including as well banned (A) sub-stances as registered veterinary medicinal products (B substances).Also in related areas, such as human doping analysis or analysis ofpesticides and contaminants, an analogous evolution of methodswas and is still ongoing.

One of the major reasons that the subject was dedicated to ourgroup is that the senior author has ca. 35 years of experience in thisarea and could look back long in the past and maybe a little bit in thefuture. At the end of the 60s, beginning of the 70s only TLC and GCwith electron capture detection (ECD) were used for the detectionof small concentrations of organic substances in complex matri-ces, next to immunological (RIA) methods. Moreover, at that timepersonal computers were non-existing. In 1973, Ghent Universityowned one computer: a so-called mainframe. Even simple calcu-lation machines – if already available – were very expensive (e.g.ca. 250D in 1977). The analytical output of instruments consistedof a (non-digital) photograph of a TLC plate or a chromatogram ofa single response of a detector in function of time on a strip chartrecorder. Nevertheless very sensitive (if we may use that word forthe detection of low concentrations) methods were developed butthe clean-up of the sample was mostly complicated and as a conse-quence sample throughput very small. An example: the price of ahormone analysis (with a limited number of substances) with TLCin 1973 was ca. 250D and only 6 analyses could be performed byone analyst in 1 week. In 2008 the price of a multi-residue analysison hormones is ca. 210D and the sample throughput is much higher(maybe a factor 10 depending upon the matrix). This comparisongives an idea of the increase of performance and sample throughputover 35 years.

For TLC as well pre- as post-development derivatisations wereused. In GC pre-column derivatisation was necessary. For ECDdetection mostly polyfluorated reagents were used. In the middle ofthe 70s also the first HPLC apparatus appeared in the laboratories.Our first HPLC with UV detection valued ca. 25,000D (a lot of moneyin that time). Since then, slowly, more and more analysis shifted toHPLC and also a differentiation between an analytical strategy forA and B substances could be made.

For A substances the battle for more specificity and lower limitsof detection intensified in the 80s by the introduction of GC–MSusing selected ion monitoring (SIM). The – at that time – highlyselective detector allowed a considerable increase in specificityas well as in detection power. Later on, SIM was more and more

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omplemented by other techniques as full-scan at low concentra-ions, MS-MS (tandem mass spectrometry), MSn (multiple masspectrometry), high resolution mass spectrometry (HRMS) andime of flight (TOF). The price of our first GC–MS system was ca.00,000D . Of course the problem of derivatisation prior to GC anal-sis remained. Only at the end of the 90s more affordable and robustC–MS-MS systems came on the market (our first system valued ca.50,000D ) and a number of laboratories shifted their GC–MS meth-ds for A substances (again) to LC–MS methods. In our laboratoryC–MS is nowadays only used for anabolic steroids.

For B substances the situation is completely different: the num-er of substances is limited and as well the substances as their MRLsre well known (ca. 120 substances in the EMEA list). Moreover,he MRL values are mostly a magnitude 10–1000× higher than the

RPLs of A substances (e.g. chloramphenicol = 0.3–100 �g/kg forulfonamides). A large number of TLC and HPLC methods with UVr post-column derivatisation have been published. However, sincea. the year 2000 more and more LC–MS analyses have been used forcreening as well as confirmation of certain groups of B substances.ccording to the 2002/657/EC one precursor and two product ionsield four identification points and fulfill the criteria needed (onlyhree IPs needed). In the future – in our view – two possible strate-ies could be followed. The first strategy is a classical one used sinceears: screening with cheap, fast methods (e.g. five plates method,LISA) and confirmation with LC–MS. For both screening and con-rmation methods the performance will improve over the comingears.

Another strategy will be the use of very sophisticated apparatusith high throughput, in which a very powerful and fast separa-

ion technique is coupled to a very powerful detection technique.n pesticide analysis so-called multi-residue methods (number ofnalytes >100) are already available. This development has – notet – reached the same level in the field of veterinary drugs. Mostethods, hitherto focused on only one class of substances but

he first papers on the simultaneous analysis of a large numberf B substances of several classes have been published recentlynd presented on international symposia. Examples are the realulti-residue methods published recently [217,218,246,253]. The

uthors use LC–MS-MS and LC–TOF-MS. What will the future bringn this area? Developments in instrumentation will go on and onnd both separation and spectroscopical techniques will grow inerformance. The use of comprehensive LC, for example, couldonsiderably increase the separation power of the methods andecrease the impact of ionisation suppression. For B substances theumber of analytes and matrices are limited and the MRL values areelatively high. One can foresee that within a decade most residuelans for B substances will be carried out on high tech multi-residue100–200 analytes) machines, controlled by intelligent supercom-uters. There will always be some molecules which – for someechnical reasons – will escape out of this multi-residue method andext to the mainstream some additional smaller methods should beun. At the end, the price for carrying out both kinds of strategiesill decide the final choice of the inspection services but we believe

igh tech machines will win the contest.For A substances the run for decreasing limits of detection will

lso stop at a certain, yet unknown stage. One reason is that themprovement of the limit of detection has revealed the naturalresence of substances formerly considered of exogenous origine.g. nortestosterone, boldenone, thiouracil) [304,305] and may doo in the future. Reference point of action (RPA) values could beome kind of equivalent to MRL values for A substances. In fact,

ome inspection services interpreted the MRPL values (Minimumequired Performance levels) already as a kind of pseudo MRLssometimes translated as Maximum Residue Permitted Level).hese pseudo MRLs require quantitatively validated methods foranned substances at very low levels, which is still challenging.

gr. A 1216 (2009) 7964–7976 7973

Another reason is that the number of analytes is theoreticallyunlimited and the number of matrices much higher than for Bsubstances (urine, faeces, bile, retina, animal feed, etc.). Multi-A-residue methods (as for B substances) will not be for the first decadewe presume. The high specificity of the detection techniques usedalso hampers the detection of “new” illegal substances at residuelevel and the search for the appearance of new “black market” prod-ucts could shift from the “bottom up” or residue laboratory stageto the “top down” or the inspection of the illegal products at pro-duction, import and distribution. Another alternative is the use ofmetabolomics and/or 12C/13C methods: in that way some kind ofpattern for “standard” animals is defined. If a sample falls outsidethat normal pattern it is suspect and the problem “to explain why”is shifted from the inspection services to the owner of the animal.

From a historical perspective, analysis of residues in meat pro-ducing animals has known a tremendous evolution during the past35–40 years. In the future, it can be foreseen that this evolutionwill proceed in the direction of the use of more and more sophisti-cated and expensive machines. These apparatus, and the necessaryhuman resources for their use, will only be affordable for labora-tories with sufficient financial resources and having the guaranteefor a sufficient throughput of samples.

Acknowledgement

The authors wish to thank M. Naessens, D. Stockx and A. Maesfor their technical contribution to this manuscript.

References

[1] L.G. Huis in’t Veld, Doc. Benelux Econom, Union SP/Lab/h, 78, 1.[2] Council Directive 1996/23/EC, Off. J. Eur. Commun. L125 (1996) 0010.[3] D. Courtheyn, B. Le Bizec, G. Brambilla, H.F. De Brabander, E. Cobbaert, M. Van

de Wiele, J. Vercammen, K. De Wasch, Anal. Chim. Acta 473 (2002) 71.[4] H.F. De Brabander, P. Batjoens, K. De Wasch, D. Courtheyn, G. Pottie, F. Smets,

Trends Anal. Chem. 16 (1997) 485.[5] A.A.M. Stolker, U.A.Th. Brinkman, J. Chromatogr. A 1067 (2005) 15.[6] K. De Wasch, S. Poelmans, T. Verslycke, C. Janssen, N. Van Hoof, H.F. De Bra-

bander, Anal Chim. Acta 473 (2002) 59.[7] S. Poelmans, K. De Wasch, D. Courtheyn, N. Van Hoof, H. Noppe, C. Janssen,

H.F. De Brabander, Anal. Chim. Acta 529 (2005) 311.[8] H.F. De Brabander, B. Le Bizec, G. Pinel, J.-P. Antignac, K. Verheyden, V. Mortier,

D. Courtheyn, H. Noppe, J. Mass Spectrom. 42 (2007) 983.[9] S. Poelmans, K. De Wasch, H. Noppe, N. Van Hoof, S. Van Cruchten, B. Le Bizec,

Y. Deceuninck, S. Sterk, H.J. Van Rossum, M.K. Hoffman, H.F. De Brabander,Food Addit. Contam. 22 (2005) 808.

[10] H.F. De Brabander, S. Poelmans, R. Schilt, R.W. Stephany, B. Le Bizec, R. Draisci,S.S. Sterk, L.A. van Ginkel, D. Courtheyn, N. Van Hoof, A. Macrì, K. De Wasch,Food Addit. Contam. 21 (2004) 515.

[11] G. Pinel, S. Mathieu, N. Cesbron, D. Maume, H.F. De Brabander, F. Andre, B. LeBizec, Food Addit. Contam. 23 (2006) 974.

[12] S. Impens, Thesis Ghent University, Ghent, Belgium, 2002, p. 201, ISBN 90-5864-025-6.

[13] H. Noppe, B. Le Bizec, K. Verheyden, H.F. De Brabander, Anal. Chim. Acta 611(2008) 1.

[14] H. Noppe, S. Poelmans, K. Verheyden, H.F. De Brabander, N. Van Hoof, VlaamsDiergen. Tijds 74 (2005) 340.

[15] D.H. Catlin, B.D. Ahrens, Y. Kucherova, Rapid Commun. Mass Spectrom. 16(2002) 1273.

[16] D.H. Catlin, M.H. Sekera, B.D. Ahrens, B. Starcevic, Y.C. Chang, C.K. Hatton,Rapid Commun. Mass Spectrom. 18 (2004) 1245.

[17] W. Karpiesiuk, A.F. Lehner, C.G. Hughes, T. Tobin, Chromatography 60 (2004)359.

[18] P. Marchand, B. Le Bizec, C. Gadé, F. Monteau, F. André, J Chromatogr. A 867(2000) 219.

[19] J. Seo, H. Kim, B.C. Chung, J. Hong, J. Chromatogr. A 1067 (2005) 303.[20] S. Hartmann, H. Steinhart, J. Chromatogr. B 704 (1997) 105.[21] B. Shao, R. Zhao, J. Meng, Y. Xue, G. Wu, J. Hu, X. Tu, Anal. Chim. Acta 548 (2005)

41.[22] M. Fuh, S. Huang, T. Lin, Talanta 64 (2004) 408.

[23] C. Blasco, C. Van Poucke, C. Van Peteghem, J. Chromatogr. A 1154 (2007) 230.[24] E. Daeseleire, R. Vandeputte, C. Van Peteghem, Analyst 123 (1998) 2595.[25] C. Buisson, M. Hebestreit, A. Preiss Weigert, K. Heinrich, H. Fry, U. Flenker,

S. Banneke, S. Prevost, F. André, W. Schaenzer, E. Houghton, B. Le Bizec, J.Chromatogr. A 1093 (2005) 69.

[26] A.A.M. Stolker, P.W. Zoontjes, L. VanGinkel, Analyst 123 (1998) 2671.

7 omato

974 H.F. De Brabander et al. / J. Chr

[27] N. Din, K.D. Bartle, A.A. Clifford, L. Castle, J. High Resolut. Chromatogr. 19 (1994)465.

[28] R.P. Huopalahti, J.D. Henion, J. Liquid Chromatogr. Relat. Technol. 19 (1996)69.

[29] H. Hooijerink, E.O. Van Bennekom, M.W.F. Nielen, Anal. Chim. Acta 483 (2003)51.

[30] M.L. Scippo, C. Van De Weerdt, P. Willemsen, J.M. Francois, F. Rentier-Delrue,M. Muller, J.A. Martial, G. Maghuin-Rogister, Anal. Chim. Acta 473 (2002)135.

[31] M.L. Scippo, P. Gaspar, G. Degand, F. Brose, G. Maghuin-Rogister, P. Delahaut,J.-P. Willemart, Anal. Chim. Acta 275 (1993) 57.

[32] M.L. Scippo, G. Degand, A. Duyckaerts, G. Maghuin-Rogister, P. Delahaut, Ana-lyst 119 (1994) 2639.

[33] C.T. Elliot, K.S. Francis, H.D. Shortt, W.J. McCaughey, Analyst 120 (1995) 1827.[34] T.L. Fodey, C.T. Elliot, S.R.H. Crooks, W.J. McCaughey, Food Agric. Immunol. 8

(1996) 157.[35] C.J.M. Arts, M.J. Van Baak, C.T. Elliot, S.A. Hewitt, J. Cooper, K. Van De Velde-

Fase, R.F. Witkamp, Analyst 123 (1998) 2579.[36] C.J.M. Arts, M.J. Van Baak (Eds.), Proceedings of Euroresidue, Noordwijkerhout,

The Netherlands, 1990, p. 105.[37] R. Verbeke, J. Chromatogr. 177 (1979) 69.[38] H.F. De Brabander, F. Smets, G. Pottie, J. Planar Chromatogr. 1 (1988) 369.[39] H.F. De Brabander, J. Van Hoof, J. Planar Chromatogr. 3 (1990) 236.[40] H.F. De Brabander, F. Smets, G. Pottie, J. Planar Chromatogr. 4 (1991) 207.[41] H.F. De Brabander, L. Hendriks, F. Smets, P. Delahaut, P. Batjoens, L. Leyssens,

G. Pottie (Eds.), Proceedings of the Euroresidue II, Veldhoven, 1993, p. 211.[42] L. Hendriks, D. Courtheyn, B. Gielen, L. Leyssens, J. Raus (Eds.), Proceedings of

the Euroresidue II, Veldhoven, 1993, p. 367.[43] P. Batjoens, H.F. De Brabander, F. Smets, G. Pottie, Analyst 119 (1994) 2607.[44] S. Impens, D. Courtheyn, K. De Wash, H.F. De Brabander, Anal. Chim. Acta 483

(2003) 269.[45] B. Le Bizec, F. Bryand, I. Gaudin, F. Monteau, F. Poulain, F. André, Steroids 67

(2002) 105.[46] C. Baronti, R. Curini, G. D’Ascenzo, A. Di Corcia, A. Gentili, R. Samperi, Environ.

Sci. Technol. 34 (2000) 5059.[47] M. Lopez de Alda, D. Barcelo, J. Chromatogr. A 892 (2000) 391.[48] M. Lopez de Alda, S. Diaz-Cruz, M. Petrovic, D. Barcelo, J. Chromatogr. A 1000

(2003) 503.[49] M.S. Diaz-Cruz, M.J. Lopez de Alda, D. Barcelo, Trends Anal. Chem. 22 (2003)

340.[50] V. Ingrad, G. Herry, J. Beausse, M. De Roubain, J. Chromatogr. A 1020 (2003)

99.[51] T. Isobe, H. Shiraishi, M. Yasuda, A. Shinoda, H. Suziki, M. Morita, J. Chromatogr.

A 984 (2003) 195.[52] A.A.M. Stolker, P.W. Zoontjes, P.L.W.J. Schwillens, P.R. Kootstra, L.A. Van Ginkel,

R.W. Stephany, U.A.Th. Brinkman, Analyst 127 (2002) 748.[53] M. Van de Wiele, K. De Wasch, J. Vercammen, D. Courtheyn, H. De Brabander,

S. Impens, J. Chromatogr. A 904 (2000) 203.[54] C. Van Poucke, C. Van Peteghem, J. Chromatogr. B 772 (2002) 211.[55] S. Poelmans, K. De Wasch, H.F. De Brabander, M. Van De Wiele, D. Courtheyn,

L.A. van Ginkel, S.S. Sterk, Ph. Delahaut, M. Dubois, R. Schilt, M. Nielen, J. Ver-cammen, S. Impens, R. Stephany, T. Hamoir, G. Pottie, C. Van Poucke, C. VanPeteghem, Anal. Chim. Acta 473 (2002) 39.

[56] R. Draisci, L. Palleschi, E. Ferretti, L. Lucentini, F. delli Quadri, J. Chromatogr. B789 (2003) 219.

[57] F. Pu, A.R. McKinney, A.M. Stenhouse, C.J. Suann, M.D. McLeod, J. Chromatogr.B 813 (2004) 241.

[58] C.L. Xu, X.G. Chu, C.F. Peng, Z.Y. Jin, L.Y. Wang, J. Pharm. Biomed. Anal. 41 (2003)616.

[59] K. Deventer, P. Van Eenoo, F.T. Delbeke, Biomed. Chromatogr. 20 (2006) 429.[60] M. Fidani, E. Casagni, M. Montana, E. Pasello, C. Pecoraro, V. Gambaro, Rapid

Commun. Mass Spectrom. 20 (2006) 2441.[61] G. Kaklamanos, G. Theodoridis, I.N. Papadoyannis, T. Dabalis, J. Agric. Food

Chem. 55 (2007) 8325.[62] K. Schmidt, C. Stachel, P. Gowik, Anal. Bioanal. Chem. 391 (2008) 1199.[63] P.B. Grace, E.C. Drake, P. Teale, E. Houghton, Rapid Commun. Mass Spectrom.

22 (2008) 2999.[64] O.J. Pozo, P. Van Eenoo, K. Deventer, F.T. Delbeke, Trends Anal. Chem. 27 (2008)

657.[65] H.F. De Brabander, Thesis Ghent University, Ghent, Belgium, 1986.[66] L. Kotter, G. Terplan, J. Schulz, Arch. Lebensmittelhyg. 10 (1959) 145.[67] H. Derblom, H. Johansson, G. Nylander, Acta Chir. Scand. 307 (Suppl.) (1963)

1.[68] H.C. Gissel, M. Schaal, Arch. Lebensmittelhyg. 1 (1974) 8.[69] M.L. Martinez-Frias, A. Cereijo, E. Rodriguez-Pinilla, M. Urioste, Lancet 339

(1992) 742.[70] Council Directive 81/602/EC, Off. J. Eur. Commun. L222 (1981) 32.[71] J. Vanden Bussche, H. Noppe, K. Verheyden, K. Wille, G. Pinel, B. Le Bizec, H.F.

De Brabander, Anal. Chim. Acta, doi:10.1016/j.aca.2008.08.027, in press.[72] P. Batjoens, H.F. De Brabander, K. De Wasch, J. Chromatogr. A 750 (1996) 127.

[73] B. Le Bizec, F. Ponteau, D. Maume, M.-P. Montrade, C. Gade, F. André, Anal.

Chim. Acta 340 (1997) 201.[74] B. Le Bizec, J.P. Antignac, E. Bichon, G. Pinel, K. Worrall, WATERS Applications

Note, 2005, 720001124EN.[75] W.J. Blanchflower, P.J. Hughers, A. Cannavan, M.A. McCoy, D.J. Kennedy, Analyst

122 (1997) 967.

gr. A 1216 (2009) 7964–7976

[76] K. De Wasch, H.F. De Brabander, S. Impens, M. Vandewiele, D. Courtheyn, J.Chromatogr. A 912 (2001) 311.

[77] G. Pinel, E. Bichon, K. Pouponneau, D. Maume, F. André, B. Le Bizec, J. Chro-matogr. A 1085 (2005) 247.

[78] S. Abuín, F. Centrich, A. Rúbies, R. Companyó, M.D. Prat, Anal. Chim. Acta 617(2008) 184.

[79] C.S. Stachel, W. Radeck, P. Gowik, Anal. Chim. Acta 493 (2003) 63.[80] N. Van Hoof, R. Schilt, E. van der Vlis, P. Boshuis, M. van Baak, A. Draaijer, K.

De Wasch, M. Van de Wiele, J. Van Hende, D. Courtheyn, H.F. De Brabander,Anal. Chim. Acta 529 (2005) 189.

[81] A. Plascencia, N. Torrentera, RA. Zinn, Proceedings of the Western Section,American Society of Animal Science, 1999, p. 50.

[82] D. Courtheyn, C. Desaever, R. Verhe, J. Chromatogr. 564 (1991) 537.[83] M.P. Montrade, B. Le Bizec, F. Monteau, B. Siliart, F. André, Anal. Chim. Acta

275 (1993) 253.[84] P.L. Wang, L. Fan, R. Song, S. Gao, X.O. Su, S.M. Yang, Chin. J. Anal. Chem. 35

(2007) 1319.[85] W. Van Thuyne, R. Van Eenoo, F.T. Delbeke, J. Chromatogr. B 1210 (2008) 193.[86] Y.C. Lei, Y.F. Tsai, Y.T. Tai, C.Y. Lin, K.H. Hsieh, T.H. Chang, S.Y. Sheu, T.F. Kuo, J.

Agric. Food Chem. 56 (2008) 5494.[87] R. Granja, A.M.M. Nino, F. Rabone, R.E.M. Nino, A. Cannavan, A.G. Salerno, Sask

Val Workshop 2007, Saskatoon, Canada, 2007, p. 1475.[88] S.A. Haughey, G.A. Baxter, J. AOAC Int. 89 (2006) 862.[89] Q. Chen, L.Y. Fan, W. Zhang, C.X. Cao, Talanta 76 (2008) 282.[90] Q.C. Chu, C.H. Geng, H. Zhou, J.N. Ye, Chin. J. Chem. 25 (2007) 1832.[91] L.D. Williams, M.I. Churchwell, D.R. Doerge, J. Chromatogr. B 813 (2004) 35.[92] J. Blanca, P. Munoz, M. Morgado, N. Mendez, A. Aranda, T. Reuvers, H. Hooghuis,

Anal. Chim. Acta 529 (2005) 199.[93] G.N.W. Leung, D.K.K. Leung, T.S.M. Wan, C.H.F. Wong, Proceedings of the 30th

International Symposium on High Performance Liquid Phase Separations andRelated Techniques, San Francisco, CA, 2006, p. 271.

[94] J.F. Huang, H.J. Zhang, B. Lin, Q.W. Yu, Y.Q. Feng, Rapid Commun. Mass Spec-trom. 21 (2007) 2895.

[95] M.W.F. Nielen, J.J.P. Lasaroms, M.L. Essers, J.E. Oosterink, T. Meijer, M.B.Sanders, T. Zuidema, A.A.M. Stolker, Anal. Bioanal. Chem. 391 (2008) 199.

[96] J.P. Antignac, K. De Wasch, F. Monteau, H.F. De Brabander, F. Andre, B. Le Bizec,Anal. Chim. Acta 529 (2005) 129.

[97] N. Van Hoof, D. Courtheyn, J.P. Antignac, M. Van de Wiele, S. Poelmans, H.Noppe, H.F. De Brabander, Rapid Commun. Mass Spectrom. 19 (2005) 1.

[98] C. Widstrand, F. Larsson, M. Fiori, C. Civitareale, S. Mirante, G. Brambilla, J.Chromatogr. B 804 (2004) 85.

[99] S. Impens, W. Reybroeck, J. Vercammen, D. Courtheyn, S. Ooghe, K. De Wasch,W. Smedts, H.F. De Brabander, Anal. Chim. Acta 483 (2003) 153.

[100] A. Conneely, A. Nugent, M. O’Keeffe, Analyst 127 (2002) 705.[101] A. Conneely, A. Nugent, M. O’Keeffe, P.P.J. Mulder, J.A. van Rhijn, L. Kovacsics,

A. Fodor, R.J. McCracken, D.G. Kennedy, Anal. Chim. Acta 483 (2003) 91.[102] M. O’Keeffe, A. Conneely, K.M. Cooper, D.G. Kennedy, L. Kovacsics, A. Fodor,

P.P.J. Mulder, J.A. van Rhijn, G. Trigueros, Anal. Chim. Acta 520 (2004) 125.[103] K.M. Cooper, C.T. Elliott, D.G. Kennedy, Food Addit. Contam. 21 (2004) 841.[104] K.M. Cooper, D.G. Kennedy, Analyst 130 (2005) 466.[105] M. Vass, L. Kotkova, I. Diblikova, Z. Nevorankova, K.M. Cooper, D.G. Kennedy,

M. Franek, Vet. Med. 50 (2005) 300.[106] K.M. Cooper, P.P.J. Mulder, J.A. van Rhijn, L. Kovacsics, R.J. McCracken, P.B.

Young, D.G. Kennedy, Food Addit. Contam. 22 (2005) 406.[107] K. De Wasch, H.F. De Brabander, D. Courtheyn, C. Van Peteghem, Analyst 123

(1998) 2415.[108] L. Istass, V. De Haan, C. Van Eenaeme, B. Buts, P. Baldwin, M. Gielen, D. Demeyer,

J.M. Bienfait, J. Anim. Physiol. Anim. Nutr. Z. TierPsychol. 62 (1989) 150.[109] S. Calvarese, P. Rubini, G. Urbani, N. Ferri, V. Ramazza, M. Zucchi, Analyst 119

(1994) 2611.[110] S.M.R. Stanley, B.S. Wilhelmi, J.P. Rodgers, J. Chromatogr. 620 (1993) 250.[111] E. Neufeld, R. Chayen, N. Stern, J. Chromatogr. B 718 (1998) 273.[112] K.E. Vanoosthuyze, L.S.G. Van Poucke, A.C.A. Deloof, C.H. Van Peteghem, Anal.

Chim. Acta 275 (1993) 177.[113] P. Volin, J. Chromatogr. B 671 (1995) 319.[114] T.A. Baillie, C.J.W. Brooks, B.S. Middleditch, Anal. Chem. 44 (1972) 30.[115] D. Courtheyn, J. Vercammen, H.F. De Brabander, I. Vandenreyt, P. Batjoens, K.

Vanoosthuyze, C. Van Peteghem, Analyst 119 (1994) 2557.[116] D. Courtheyn, J. Vercammen, M. Logghe, H. Seghers, K. De Wasch, H.F. De

Brabander, Analyst 123 (1998) 2409.[117] G.R. Her, J.T. Watson, Biomed. Environ. Mass Spectrom. 13 (1986) 57.[118] O.H. Hidalgo, M.J. Lopez, E.A. Carazo, M.S. Larrea, T.B.A. Reuvers, J. Chromatogr.

B 788 (2003) 137.[119] T. Cairns, E.G. Siegmund, J.J. Stamp, J.P. Skelly, Biomed. Mass Spectrom. 10

(1983) 203.[120] J.P. Antignac, B. Le Bizec, F. Monteau, F. Poulain, F. André, Rapid Commun. Mass

Spectrom. 14 (2000) 33.[121] G. Brambilla, F. Buiarelli, G.P. Cartoni, F. Coccioli, C. Colamonici, A. Fagiolo, C.

Giannini, B. Neri, J. Chromatogr. B 755 (2001) 265.[122] R. Draisci, C. Marchiafava, L. Palleschi, P. Cammaratta, S. Cavalli, J. Chromatogr.

B 753 (2001) 217.[123] M. O’Keeffe, S. Martin, L. Regan, Anal. Chim. Acta 483 (2003) 341.[124] O. Van den Hauwe, F. Dumoulin, J.P. Antignac, M.P. Bouche, C. Elliott, C. Van

Peteghem, Anal. Chim. Acta 473 (2002) 127.[125] O. Van den Hauwe, M. Schneider, A. Sahin, C. Van Peteghem, H. Naegeli, J.

Agric. Food Chem. 51 (2003) 326.

omato

H.F. De Brabander et al. / J. Chr

[126] M.E. Touber, M.C. Van Engelen, C. Georgakopoulus, J.A. Van Rhijn, M.W.F. Nie-len, Anal. Chim. Acta 586 (2007) 137.

[127] M.H. Blokland, S.S. Sterk, L.A. van Ginkel, R.W. Stephany, A.J.R. Heck, Anal.Chim. Acta 438 (2003) 201.

[128] T.H.J. Heutmekers, M.G.E.G. Bremer, W. Haasnoot, M.W.F. Nielen, Anal. Chim.Acta 586 (2007) 239.

[129] G. Pinel, R. Buon, F. Avikat, C. Larré, G. André-Fontaine, F. André, B. Le Bizec,Anal. Chim. Acta 529 (2005) 41.

[130] N. Rochut, B. Le Bizec, F. Monteau, F. André, Analysis 28 (2000) 280.[131] N. Chaiyabutr, S. Komolvanich, S. Thammacharoen, S. Chanpongsang, Anim.

Sci. J. 79 (2008) 561.[132] M.T. Rose, T.E.C. Weekes, P. Rowlinson, Domest. Anim. Endocrinol. 36 (2009)

24.[133] J. Bijman, Biotechnol. Develop. Monitor. 27 (1996) 2.[134] J. Serratosa, A. Blass, B. Rigau, B. Mongrell, T. Rigau, M. Tortadès, E. Tolosa, C.

Aquilar, O. Ribó, J. Balagué, Rev. Sci. Tech. Off. Int. Epiz. 25 (2006) 637.[135] M.H. LeBreton, S.R.L. Bailly-Chouriberry, G. Rychen, S. Jurjanz, T. Goldmann, B.

Le Bizec, Rapid Commun. Mass Spectrom. 22 (2008) 3130.[136] C.M. Zwickl, H.W. Smith, P.H. Bick, J. Agric. Food Chem. 38 (1990) 1358.[137] A. Guidi, L. Laracchia-Robbio, D. Gianfaldoni, R. Revoltella, G. Del Bono, Pro-

ceedings Paper Biosensors and Bioelectronics 16 (2001), 9.[138] G. Pinel, F. André, B. Le Bizec, J. Agric. Food Chem. 52 (2004) 407.[139] R. Zvirdauskiene, J. Salomskiene, Food Control 18 (2007) 541.[140] G.O. Korsrud, J.O. Boison, J.F.M. Nouws, J.D. MacNeil, J. AOAC Int. 81 (1998) 21.[141] V. Gaudin, P. Maris, R. Fuselier, J.-L. Ribouchon, N. Cadieu, A. Rault, Food Addit.

Contam. 21 (2004) 422.[142] A.-L. Myllyniemi, L. Nuotio, E. Lindfors, R. Rannikko, A. Niemi, C. Bäckman,

Analyst 126 (2001) 641.[143] M.G. Pikkemaat, S. Oostra-van Dijk, J. Schouten, M. Rapallini, H.J. van Egmond,

Food Control 19 (2008) 781.[144] L. Okerman, S. Croubels, M. Cherlet, K. De Wasch, P. De Backer, J. Van Hoof,

Food Addit. Contam. 21 (2004) 145.[145] L. Okerman, H. Noppe, V. Cornet, L. De Zutter, Food Addit. Contam. 24 (2007)

252.[146] M.G. Pikkemaat, P.P.J. Mulder, J.W.A. Elferink, A. de Cocq, M.W.F. Nielen, H.J.

van Egmond, Food Addit. Contam. 24 (2007) 842.[147] L. Okerman, S. Croubels, S. De Baere, J. Van Hoof, P. De Backer, H.F. De Braban-

der, Food Addit. Contam. 18 (2001) 385.[148] T. Honkanen-Buzalski, W. Reybroeck, Antimicrobials, I.D.F, Brussels, Belgium,

1997, ISBN 92 9098 025 8, p. 28, (1997, ISBN 92 9098 024 7).[149] A.H. Knight, N. Shapton, G.A. Prentice, Int. J. Dairy Technol. 40 (2007) 30.[150] W. Reybroeck, Proceedings of the “I.D.F.-Symposium on Residues of Antimi-

crobial Drugs and other Inhibitors in Milk, Kiel, Germany”, IDF, Brussels, 1995,p. 182.

[151] W. Reybroeck, Proceedings of the “I.D.F.-Symposium on Residues of Antimi-crobial Drugs and other Inhibitors in Milk, Kiel, Germany”, IDF, Brussels, 1995,p. 216.

[152] S. Kroll, Inaugural-Dissertation zur Erlangung der tiermedizinischen Dok-torwürde der Tierärztlichen Fakultät der Ludwig-Maximilians-UniversitätMünchen, Deutschland, 2000, p. 1.

[153] S.P. Huth, P.S. Warholic, J.M. Devou, L.K. Chaney, G.H. Clark, J. AOAC Int. 85(2002) 355.

[154] Anonymous, Food Safety Authority of Ireland, Dublin, Ireland, 2002, p. 1.[155] W. Reybroeck, Point Vet. 242 (2004) 52.[156] W. Reybroeck, S. Ooghe, Proceedings of the IDF/FAO International Symposium

on Dairy Safety and Hygiene, Cape Town, Rep. of South-Africa, 2004, p. 157,ISSN 1810-0732.

[157] W. Reybroeck, S. Ooghe, in: L.A. Van Ginkel, A.A. Bergwerff (Eds.), Proceedingsof the EuroResidue VI Conference, Egmond aan Zee (The Netherlands), 2008,ISBN 978-90-804925-3-0, p. 787.

[158] W. Reybroeck, S. Ooghe, in: L.A. Van Ginkel, A.A. Bergwerff (Eds.), Proceedingsof the EuroResidue VI Conference, Egmond aan Zee (The Netherlands), 2008,ISBN 978-90-804925-3-0, p. 793.

[159] W. Reybroeck, S. Ooghe, Abstract in Abstract Book 5th International Sympo-sium on Hormone and Veterinary Drug Residue Analysis, Antwerp, 2006, p.26.

[160] W. Reybroeck, S. Ooghe, H. De Brabander, E. Daeseleire, J. AOAC Int., submittedfor publication.

[161] R.J. Markovsky, D.W. Douglas, in: L.A. Van Ginkel, A.A. Bergwerff (Eds.),Proceedings of the EuroResidue VI Conference, Egmond aan Zee (The Nether-lands), 2008, ISBN 978-90-804925-3-0, p. 695.

[162] W. Reybroeck, S. Ooghe, H. De Brabander, E. Daeseleire, J. Agric. Food Chem.55 (2007) 8359.

[163] G.O. Korsrud, C.D. Salisbury, A.C. Fesser, J.D. MacNeil, Analyst 119 (1994)2737.

[164] E. Märtlbauer, E. Usleber, E. Schneider, R. Dietrich, Analyst 119 (1994) 2543.[165] J.M. Mitchell, M.W. Griffiths, S.A. McEwen, W.B. McNab, A.J. Yee, J Food Prot.

61 (1998) 742.[166] E. Gustavsson, P. Bjurling, Å. Sternesjö, Anal. Chim. Acta 468 (2002) 153.[167] M.M. Pilar, A. Javier, R. Javier, S.J. Pablo, Francisco Sanchez-Baeza, in: L.A. Van

Ginkel, A.A. Bergwerff (Eds.), Proceedings of the EuroResidue VI Conference,Egmond aan Zee (The Netherlands), 2008, ISBN 978-90-804925-3-0, p. 181.

[168] M.E. Bienenmann-Ploum, W. de Keizer, H.D.L.M. van Eekelen, A.A. Bergwerff,W. Haasnoot, M.W.F. Nielen, in: L.A. Van Ginkel, A.A. Bergwerff (Eds.), Proceed-ings of the EuroResidue VI Conference, Egmond aan Zee (The Netherlands),2008, ISBN 978-90-804925-3-0, p. 425.

gr. A 1216 (2009) 7964–7976 7975

[169] A. Tohill, D. McAleer, R. Acheson, B. Bell, R.I. McConnell, S.P. FitzGerald, in: L.A.Van Ginkel, A.A. Bergwerff (Eds.), Proceedings of the EuroResidue VI Confer-ence, Egmond aan Zee (The Netherlands), 2008, ISBN 978-90-804925-3-0, p.1379.

[170] S.L. Stead, in: L.A. Van Ginkel, A.A. Bergwerff (Eds.), Proceedings of theEuroResidue VI Conference, Egmond aan Zee (The Netherlands), 2008, ISBN978-90-804925-3-0, p. 23.

[171] M. McGrane, M. O’Keeffe, M.R. Smyth, Analyst 123 (1998) 2779.[172] T. Reyns, M. Cherlet, S. De Baere, P. De Backer, S. Croubels, J. Chromatogr. B 861

(2008) 108.[173] K. Mastovska, A.R. Lightfield, J. Chromatogr. A 1202 (2008) 118.[174] C.K. Fagerquist, A.R. Lightfield, S.J. Lehotay, Anal. Chem. 77 (2005) 1473.[175] M. Becker, E. Zittlau, M. Petz, Anal. Chim. Acta 520 (2004) 19.[176] T. Reyns, S. De Boever, S. De Baere, P. De Backer, S. Croubels, Anal. Chim. Acta

597 (2007) 282.[177] S. Bogialli, R. Curini, A. Di Corcia, M. Nazzari, M.L. Polci, J. Agric. Food Chem.

51 (2003) 4225.[178] G.Z. Fang, J.X. He, S. Wang, J. Chromatogr. A 1127 (2006) 12.[179] A. Gentili, D. Perret, S. Marchese, M. Sergi, C. Olmi, R. Curini, J. Agric. Food

Chem. 52 (2004) 4614.[180] B. Shao, D. Dong, Y.N. Wu, J.Y. Hu, J. Meng, X.M. Tu, S.K. Xu, Anal. Chim. Acta

546 (2005) 174.[181] S. De Baere, K. Baert, S. Croubels, J. De Busser, K. De Wasch, P. De Backer, Analyst

125 (2000) 409.[182] M. Sergi, A. Gentili, D. Perret, S. Marchese, S. Materazzi, R. Curini, Chromatog-

raphy 65 (2007) 757.[183] R. Mohamed, Y.A. Hammel, M.H. LeBreton, J.C. Tabet, L. Jullien, P.A. Guy, J.

Chromatogr. A 1160 (2007) 194.[184] R. Sheridan, B. Policastro, S. Thomas, D. Rice, J. Agric. Food Chem. 56 (2008)

3509.[185] M. Cherlet, M. Schelkens, S. Croubels, P. De Backer, Anal. Chim. Acta 492 (2003)

199.[186] M. Cherlet, P. De Backer, S. Croubels, J. Chromatogr. A 1133 (2006) 135.[187] S. Bogialli, R. Curini, A. Di Corcia, A. Lagana, G. Rizzuti, J. Agric. Food Chem. 54

(2006) 1564.[188] A. Posyniak, K. Mitrowska, J. Zmudzki, J. Niedzielska, J. Chromatogr. A 1088

(2005) 169.[189] M. Cherlet, S. De Baere, P. De Backer, Analyst 128 (2003) 871.[190] F. Capolongo, A. Santi, L. Tomasi, P. Anfossi, M. Missagia, C. Montesissa, J. AOAC

Int. 85 (2002) 8.[191] W.J. Blanchflower, R.J. McCracken, A.S. Haggan, D.G. Kennedy, J. Chromatogr.

B 692 (1997) 351.[192] S. Bogialli, C. Coradazzi, A. Di Corcia, A. Lagana, M. Sergi, J. AOAC Int. 90 (2007)

864.[193] M.P. Hermo, D. Barron, J. Barbosa, J. Chromatogr. A 1104 (2006) 132.[194] S. Bogialli, G. D’Ascenzo, A. Di Corcia, G. Innocenti, A. Lagana, T. Pacchiarotta,

Rapid Commun. Mass Spectrom. 21 (2007) 2833.[195] M. Clemente, M.P. Hermo, D. Barron, J. Barbosa, J. Chromatogr. A 1135 (2006)

170.[196] S. Bailac, D. Barron, J. Barbosa, Anal. Chim. Acta 580 (2006) 163.[197] K. Hatano, J. Food Hyg. Soc. Jpn. 45 (2004) 239.[198] B. Toussaint, G. Bordin, A. Janosi, A.R. Rodriguez, J. Chromatogr. A 976 (2002)

195.[199] N. Van Hoof, K. De Wasch, L. Okerman, W. Reybroeck, S. Poelmans, H. Noppe,

H. De Brabander, Anal. Chim. Acta 529 (2005) 265.[200] M.P. Heymo, E. Nemutlu, S. Kir, D. Barron, J. Barbosa, Anal. Chim. Acta 613

(2008) 98.[201] P. Mottier, Y.A. Hammel, E. Gremaud, P.A. Guy, J. Agric. Food Chem. 56 (2008)

35.[202] C.M. Karbiwnyk, L.E. Carr, S.B. Turnipseed, W.C. Andersen, K.E. Miller, Anal.

Chim. Acta 596 (2007) 257.[203] V. Samanidou, E. Evaggelopoulou, M. Trotzmuller, X.H. Guo, E. Lankmayr, J.

Chromatogr. A 1203 (2008) 115.[204] S. Herranz, M.C. Moreno-Bondi, M.D. Marazuela, J. Chromatogr. A 1140 (2007)

63.[205] Z.F. Yue, X.X. Chen, L.Q. Xie, C.N. Ji, H.H. Hua, Chin. J. Anal. Chem. 35 (2007)

1290.[206] R. Draisci, L. Palleschi, E. Ferretti, L. Achene, A. Cecilia, J. Chromatogr. A 926

(2001) 97.[207] P.A. Martos, S.J. Lehotay, B. Schurmer, J. Agric. Food Chem. 56 (2008) 8844.[208] W.X. Zhu, J.Z. Yang, W. Wei, Y.F. Liu, S.S. Zhang, J. Chromatogr. A 1207 (2008)

29.[209] Y. Babin, S. Fortier, J. AOAC Int. 90 (2007) 1418.[210] S. Bogialli, R. Curini, A. Di Corcia, A. Lagana, M. Mele, M. Nazzari, J. Chromatogr.

A 1067 (2005) 93.[211] J.M. Van De Riet, R.A. Potter, M. Christie-Fougere, B.G. Burns, J. AOAC Int. 86

(2003) 510.[212] C.L. Wrzesinski, L.S. Crouch, R. Endris, J. AOAC Int. 86 (2003) 515.[213] D.W.M. Sin, C. Ho, Y.C. Wong, S.K. Ho, A.C.B. Ip, Anal. Chim. Acta 535 (2005)

23.

[214] U. Vincent, M. Chedin, S. Yasar, C. von Holst, J. Pharm. Biomed. Anal. 47 (2008)

750.[215] M. Rokka, K. Peltonen, Food Addit. Contam. 23 (2006) 470.[216] D.K. Matabudul, B. Conway, I. Lumley, S. Sumar, Food Chem. 75 (2001) 345.[217] R. Yamada, M. Kozono, T. Ohmori, F. Morimatsu, M. Kitayama, Biosci. Biotech-

nol. Biochem. 70 (2006) 54.

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179.[303] N. Van Hoof, K. De Wasch, S. Poelmans, H. Noppe, H.F. De Brabander, Rapid

976 H.F. De Brabander et al. / J. Chr

[218] K. Granelli, C. Branzell, Anal. Chim. Acta 586 (2007) 289.[219] V. Carretero, C. Blasco, Y. Pico, J. Chromatogr. A 1209 (2008) 162.220] H.P.O. Tang, C. Ho, S.S.L. Lai, Rapid Commun. Mass Spectrom. 20 (2006) 2565.

[221] C. Li, Z.H. Wang, X.Y. Cao, R.C. Beier, S.X. Zhang, S.Y. Ding, X.W. Li, J.Z. Shen, J.Chromatogr. A 1209 (2008) 1.

222] Y.A. Hammel, R. Mohamed, E. Gremaud, M.H. LeBreton, P.A. Guy, J. Chromatogr.A 1177 (2008) 58.

223] M.I. Lopez, J.S. Pettis, I.B. Smith, P.S. Chu, J. Agric. Food Chem. 56 (2008) 1553.224] S.B. Turnipseed, W.C. Andersen, C.M. Karbiwnyk, M.R. Madson, K.E. Miller,

Rapid Commun. Mass Spectrom. 22 (2008) 1467.225] D.N. Heller, C.B. Nochetto, N.G. Rummel, M.H. Thomas, J. Agric. Food Chem. 54

(2006) 5267.226] D.N. Heller, C.B. Nochetto, J. Agric. Food Chem. 52 (2004) 6848.

[227] H. Li, P.J. Kijak, S.B. Turnipseed, W. Cui, J. Chromatogr. B 836 (2006) 22.228] A. Gentili, D. Perret, S. Marchese, Trends Anal. Chem. 24 (2005) 704.229] V. Samanidou, S. Nisyriou, J. Sep. Sci. 31 (2008) 2068.230] S.I. Kotretsou, Crit. Rev. Food Sci. Nutr. 44 (2004) 173.

[231] H. Oka, Y. Ito, Y. Ikai, T. Kagami, K. Harada, J. Chromatogr. A 812 (1998) 309.232] D.G. Kennedy, R.J. McCracken, A. Cannavan, S.A. Hewitt, J. Chromatogr. A 812

(1998) 77.233] W.M.A. Niessen, J. Chromatogr. A 812 (1998) 53.234] T.A. McGlinchey, P.A. Rafter, F. Regan, G.P. McMahon, Anal. Chim. Acta 624

(2008) 1.235] V.F. Samanidou, E.P. Tolika, I.N. Papadoyannis, Sep. Purif. Rev. 37 (2008) 327.236] J. Wang, Mass Spectrom. Rev. 28 (2009) 50.

[237] M.M. Aguilera-Luiz, J.L.M. Vidal, R. Romero-González, A.G. Frenich, J. Chro-matogr. A 1205 (2008) 10.

238] G. Stubbings, J. Tarbin, A. Cooper, M. Sharman, T. Bigwood, P. Robb, Anal. Chim.Acta 547 (2005) 262.

239] A.G.V. de Prada, O.A. Loaiza, B. Serra, D. Morales, P. Martinez-Ruiz, A.J. Reviejo,J.M. Pingarron, Anal. Bioanal. Chem. 388 (2007) 227.

240] X.G. Hu, J.L. Pan, Y.L. Hu, Y. Huo, G.K. Li, J. Chromatogr. A 1188 (2008) 97.[241] J.X. He, S. Wang, G.Z. Fang, H.P. Zhu, Y. Zhang, J. Agric. Food Chem. 56 (2008)

2919.242] H.Y. Yan, F.X. Qiao, K.H. Row, Anal. Chem. 79 (2007) 8242.243] E. Caro, R.M. Marce, P.A.G. Cormack, D.C. Sherrington, F. Borrull, Anal. Chim.

Acta 552 (2005) 81.244] J. Wang, D. Leung, Rapid Commun. Mass Spectrom. 21 (2007) 3213.245] A.A.M. Stolker, P. Rutgers, E. Oosterink, J.J.P. Lasaroms, R.J.B. Peters, J.A. van

Rhijn, M.W.F. Nielen, Anal. Bioanal. Chem. 391 (2008) 2309.246] A. Kaufmann, P. Butcher, K. Maden, M. Widmer, Anal. Chim. Acta 586 (2007)

13.[247] A. Kaufmann, P. Butcher, K. Maden, M. Widmer, J. Chromatogr. A 1194 (2008)

66.248] A. Carrasco-Pancorbo, S. Casado-Terrones, A. Segura-Carretero, A. Fernandez-

Gutierrez, J. Chromatogr. A 1195 (2008) 107.249] M.P. Hermo, D. Barron, J. Barbosa, J. Chromatogr. A 1201 (2008) 1.250] G.R. Marchesini, W. Haasnoot, P. Delahaut, H. Gercek, M.W.F. Nielen, Anal.

Chim. Acta 586 (2007) 259.[251] X.S. Miao, R.E. March, C.D. Metcalfe, Int. J. Mass Spectrom. 230 (2003) 123.252] G. Kesiünaite, E. Naujalis, A. Padarauskas, J. Chromatogr. A 1209 (2008) 83.253] J. Chico, A. Rúbies, F. Centrich, R. Companyó, M.D. Prat, M. Granados, J. Chro-

matogr. A 1213 (2008) 189.254] Z.X. Cai, Y. Zhang, H.F. Pan, X.W. Tie, Y.P. Ren, J. Chromatogr. A 1200 (2008)

144.255] V. Tamosiunas, A. Padarauskas, Chromatography 67 (2008) 783.256] B. Shao, X. Jia, Y. Wu, J. Hu, X. Tu, J. Zhang, Rapid Commun. Mass Spectrom. 21

(2007) 3487.[257] M. Danaher, H. De Ruyck, S.R.H. Crooks, G. Dowling, M. O’Keeffe, J. Chromatogr.

B 845 (2007) 1.258] G. Dowling, H. Cantwell, M. O’Keeffe, M.R. Smyth, Anal. Chim. Acta 529 (2005)

285.259] H. De Ruyck, E. Daeseleire, H. De Ridder, R. Van Renterghem, J. Chromatogr. A

976 (2002) 181.260] G. Stoev, T. Dakova, A. Michaelova, J. Chromatogr. A 846 (1999) 383.

[261] H.W. Sun, F.C. Wang, L.F. Ai, J. Chromatogr. A 1175 (2007) 227.262] H.W. Sun, F.C. Wang, L.F. Ai, J. Chromatogr. Sci. 46 (2008) 351.263] M. Cherlet, S. De Baere, S. Croubels, P. De Backer, J. Chromatogr. B 742 (2000)

283.

gr. A 1216 (2009) 7964–7976

[264] D.A. Durden, J. Chromatogr. B 850 (2007) 134.[265] X.L. Hou, Y.N. Wu, J.Z. Shen, L. Wang, S.Y. Ding, Chromatography 65 (2007) 77.[266] X.L. Hou, H.Y. Jiang, S.Y. Ding, S.X. Zhang, X.W. Li, J.Z. Shen, J. AOAC Int. 89

(2006) 1110.[267] L. Howells, M.J. Sauer, Analyst 126 (2001) 155.[268] Z.G. Wu, J.S. Li, L. Zhu, H.P. Luo, X.J. Xu, J. Chromatogr. B 755 (2001) 361.[269] M. Dubois, G. Pierret, P. Delahaut, J. Chromatogr. B 813 (2004) 181.[270] L. Mortier, A.C. Huet, C. Charlier, E. Daeseleire, P. Delahaut, C. Van Peteghem,

Food Addit. Contam. 22 (2005) 1120.[271] T. Kumazawa, O. Suzuki, J. Chromatogr. B 747 (2000) 241.[272] F. Koc, Y. Yigit, Y.K. Das, Y. Gurel, C. Yaral, J. Food Drug Anal. 16 (2008) 39.[273] A.N. Diaz, A.G. Pareja, F.G. Sanchez, Pest. Sci. 49 (1997) 56.[274] M. Cossu, M.C. Alamanni, Ital. J. Food Sci. 15 (2003) 541.[275] Z.M. Chen, Y.H. Wang, J. Chromatogr. A 754 (1996) 367.[276] H.J. Keukens, M.L. Aerts, J. Chromatogr. 464 (1989) 149.[277] R.F. Tyndale, T. Inaba, J. Chromatogr. 529 (1990) 182.[278] M.L. Macho, P. Munoz, Proceedings of the Euroresidue II, Veldhoven, NL, 1993,

p. 465.[279] S. Porter, R.A.J. Patel, N. Johnston, Proceedings of the EuroResidue II Conference

on Residues of Veterinary Drugs in Food, Veldhoven, The Netherlands, 1993.[280] W. Arneth, Z. Lebensm, Unters. Forsch. 201 (1995) 264.[281] J. Cooper, Ph. Delahaut, T.L. Fodey, Chr.T. Elliott, Analyst 129 (2004) 169.[282] Y. Govaert, P. Batjoens, K. Tsilikas, J.-M. Degroodt, S. Srebrnik, Analyst 123

(1998) 2507.[283] P. Batjoens, K. Tsilikas, Y. Goevaert, J.-M. Degroodt, S. Srebnik, Proceedings

of the EuroResidue II Conference on Residues of Veterinary Drugs in Food,Veldhoven, The Netherlands, 2000, p. 208.

[284] D. Fluchard, S. Kiebooms, M. Dubois, Ph. Delahaut, J. Chromatogr. B 744 (2000)139.

[285] Ph. Delahaut, C. Levaux, P. Eloy, M. Dubois, Anal. Chim. Acta 483 (2003) 335.[286] Ph. Delahaut, P.-Y. Brasseur, M. Dubois, J. Chromatogr. A 1054 (2004) 373.[287] E. Daeseleire, L. Mortier, H. De Ruyck, N. Geerts, Anal. Chim. Acta 488 (2003)

25.[288] P.L. Boner, D.D.W. Liu, W.F. Feely, R.A. Robinson, J. Wu, J. Agric. Food Chem. 51

(2003) 7555.[289] P.L. Boner, D.D.W. Liu, W.F. Feely, M.J. Wisocky, J. Wu, J. Agric. Food Chem. 51

(2003) 3753.[290] P. Van Eenoo, F.T. Delbeke, K. Roels, K. Baert, J. Pharm. Biomed. Anal. 31 (2003)

723.[291] H.S. Rupp, D.C. Holland, R.K. Munns, S.B. Turnipseed, A.R. Long, J. AOAC Int. 79

(1995) 959.[292] S.M.R. Stanley, N.A. Owens, J.P. Rodgers, J. Chromatogr. B: Biomed. Appl. 667

(1995) 95.[293] A.K. Singh, Y. Jang, U. Mishra, K. Granley, J. Chromatogr. B: Biomed. Appl. 106

(1991) 351.[294] V. Hormazabal, M. Yndestad, J. Liq. Chromatogr. Relat. Technol. 24 (2001)

2477.[295] M.E. Abdel-Hamid, L. Novotny, H. Hamza, J. Pharm. Biomed. Anal. 24 (2001)

587.[296] S.B. Clark, S.B. Turnipseed, G.J. Nandrea, M.R. Madson, J.A. Hurlbut, J.N. Sofos,

J. AOAC Int. 85 (2002) 1009.[297] P.A. Asea, J.R. Patterson, G.O. Korsrud, P.M. Dowling, J.O. Boison, J. AOAC Int.

84 (2001) 659.[298] J.L. Wiesner, A.D. de Jager, F.C.W. Sutherland, H.K.L. Hundt, K.J. Swart, A.F.

Hundt, J. Els, J. Chromatogr. B 785 (2003) 115.[299] M.I.G. Martin, C.I.S. Gonzales, A.J. Hernandez, M.D.G. Cachan, M.J.C. de Cabo,

A.L.G. Cuadrado, J. Chromatogr. B 769 (2002) 119.[300] Y. Luo, J.A. Rudy, C.E. Uboh, L.R. Soma, F. Guan, J.M. Enright, D.S. Tsang, J.

Chromatogr. B 801 (2004) 173.[301] J.Y. Kim, S.J. Kim, K.J. Paeng, B.C. Chung, J. Vet. Pharmacol. Ther. 24 (2001) 315.[302] S. Croubels, A. Maes, K. Baert, P. De Backer, Anal. Chim. Acta 529 (2005)

Commun. Mass Spectrom. 18 (2004) 1.[304] G. Pinel, D. Maume, Y. Deceuninck, F. André, B. Le Bizec, Rapid Commun. Mass

Spectrom. 20 (2006) 3183.[305] H.F. De Brabander, Thesis Ghent University, Ghent, Belgium, 2003.