Analyst

PAPER

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0F

View Article OnlineView Journal | View Issue

aFaculty of Science and Engineering, Scho

Division of Chemistry and Environmen

University, Chester Street, Manchester M1

ac.uk; Fax: +44 (0)1612476831; Tel: +44 (0)bDepartamento de Quımica, Universidade F

Exatas e de Tecnologia, 676, P.O. Box 676,

† Electronic supplementary informa10.1039/c2an36450f

‡ Visiting student from: Cesi School of En602, 92006 Nanterre Cedex, France.

Cite this: Analyst, 2013, 138, 1053

Received 8th October 2012Accepted 20th December 2012

DOI: 10.1039/c2an36450f

www.rsc.org/analyst

This journal is ª The Royal Society of

Forensic electrochemistry: sensing the molecule ofmurder atropine†

Ouissam Ramdani,‡a Jonathan P. Metters,a Luiz Carlos S. Figueiredo-Filho,b

Orlando Fatibello-Filhob and Craig E. Banks*a

We present the electroanalytical sensing of atropine using disposable and economic screen printed

graphite sensors. The electroanalytical determination of atropine is found to be possible over the

concentration range of 5 mM to 50 mM with a detection limit of 3.9 mM (based on 3-sigma) found to be

possible. We demonstrate proof-of-concept that this approach provides a rapid and inexpensive sensing

strategy for determining the molecule of murder atropine in diet Coca-Cola samples.

Scheme 1 The molecule of murder: atropine.

Introduction

Atropine takes its name aer the Greek legend Atropos, one ofthe three Greek Fates who cut people's lives short. Atropine is atropane alkaloid which may be extracted from the Solanaceaeplant family such as Datura stramonium (jimsonweed) andAtropa belladonna (deadly nightshade).1 Atropine, the chemicalstructure of which is shown in Scheme 1, has anticholinergicactivity resulting in blurred vision, vasodilation, increased heartrate and delirium.2 However, it has medical uses such asreducing rigidity in Parkinsonism and is used as an antidote topoisoning with parasympathomimetic agents such as nervegases.2

Atropine poisoning has been reported1,3 and one of the mostinteresting cases of using atropine as a deadly poison is the caseof Dr Paul Agutter in 1994 who attempted to murder his wife byspiking her favourable tipple of gin and tonic.4 Agutter tried tocover his tracks by entering his local supermarket in Edinburghand purchasing a dozen or so bottles of tonic water. Agutterdeliberately spiked these will atropine and returned all but onebottle back onto the supermarket shelves.5,6 The idea was to foolthe police into thinking that a criminal was trying to blackmailthe supermarket and that Agutter's wife, who frequently shop-ped there, had unfortunately purchased a tampered bottle oftonic water. Agutter did not succeed in his endeavours but wasfound guilty of attempted murder in 1995; aer serving his

ol of Chemistry and the Environment,

tal Science, Manchester Metropolitan

5GD, Lancs, UK. E-mail: c.banks@mmu.

1612471196

ederal de S~ao Carlos, Centro de Ciencias

13560-970, S~ao Carlos, S~ao Paulo, Brazil

tion (ESI) available. See DOI:

gineering, 93 boulevard de la seine, BP

Chemistry 2013

punishment, Agutter found employment lecturing at Man-chester University on philosophy and ethics.4,7

Current analytical methods for determining atropine includeHigh Performance Liquid Chromatography2,8 and Gas Chro-matography-Mass Spectrometry9 but are limited due to highcost and sample preparation and are unattractive where a rapidand portable sensing approach may be required.

An analytical approach which can be used in niche applica-tions to overcome these limitations are electrochemical sensorswhich are advantageous due to their potential miniaturisation,portability and low cost, with technology developed in thelaboratory translated in to the eld with the use of screenprinted electrodes.10 We note that there is only one reportdescribing the electrochemical detection of atropine usinguncharacterised multi-walled carbon nanotubes incorporatedinto a paste electrode coupled with the surfactant sodiumdodecyl benzene sulfonate which was applied for the determi-nation of atropine in eye drops.11 We also note that there areliterature reports of ion-selective electrodes,12,13 electro-chemiluminescence detection,14 and non-aqueous capillaryelectrophoresis coupled with electrochemiluminescence andelectrochemistry dual detection,15 though these are indirectelectrochemical measurements.

In this paper we demonstrate for the rst time, the electro-chemical sensing of atropine utilising disposable and costeffective screen printed graphite electrodes without therequirement for any pre-treatment or surface modication. The

Analyst, 2013, 138, 1053–1059 | 1053

Analyst Paper

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

analytical performance and robust nature of the screen printedsensors is explored within both ‘ideal’ buffers and diluted dietCoca-Cola. Note that the potential use of surfactants, as hasbeen previously reported,11 for improved analytical performancetowards the sensing of atropine is also critically and extensivelyexplored.

Fig. 1 Cyclic voltammetric responses recorded at an edge plane pyrolyticgraphite electrode (vs. SCE) in 1 mM atropine in pH 10 buffer solution. Scan rate:100 mV s�1.

Experimental section

All chemicals used were of analytical grade and were used asreceived without any further purication and were obtainedfrom Sigma-Aldrich. All solutions were prepared with deionisedwater of resistivity not less than 18.2 MU cm.

Voltammetric measurements were carried out using a m-Autolab III (ECO-Chemie, The Netherlands) potentiostat. Allmeasurements were conducted using a screen-printed electrodeconguration. Screen-printed carbon electrodes were fabricatedin-house with appropriate stencil designs using a microDEK1760RS screen-printing machine (DEK, Weymouth, UK). Acarbon-graphite ink formulation previously utilised16 was rstscreen printed onto a polyester exible lm (Autostat, 250 mmthickness). This layer was cured in a fan oven at 60 degrees for30 minutes. Next a silver/silver chloride reference electrode wasincluded by screen printing Ag/AgCl paste (Gwent ElectronicMaterials Ltd, UK) on to the plastic substrate. Last a dielectricpaste ink (Gwent Electronic Materials Ltd, UK) was printed tocover the connections and dene the 3 mm diameter graphiteworking electrode. Aer curing at 60 degrees for 30 minutes thescreen printed electrode is ready to use. These electrodes havebeen reported before and used for the sensing of chro-mium(VI),17 methionine,18 cytochrome C19 and more recentlyselenium;20 such applications highlight the variety of analytesthat can be readily detected using screen printed graphiteelectrodes.

The buffers utilised throughout were phosphate buffersolutions with pH modications made utilising either concen-trated hydrochloric acid or sodium hydroxide. Both diet Coca-Cola and Indian Tonic Water were purchased from a localconvenience store and diluted in a 1 : 1 ratio with pH 10phosphate buffer and adjusted to pH 10 with the addition ofsodium hydroxide. These diluted samples was stored at roomtemperature and used within a day of purchase.

Results and discussionOptimisation of the electrochemical protocol

The electrochemical sensing of atropine was rst explored at arange of commonly available electrode substrates. Fig. 1 revealsthat the electrochemical oxidation of atropine is possible were alarge and easily quantiable voltammetry signature is observedusing an edge plane pyrolytic graphite electrode with the vol-tammetric signature occurring at �+0.86 V (vs. SCE). Similarly,an oxidation wave can be observed using a basal plane pyrolyticgraphite electrode at a potential of �+0.95 V (vs. SCE) while at aplatinum macroelectrode a voltammetric wave is exhibited at apotential of �+1.3 V (vs. SCE) while no voltammetric waves were

1054 | Analyst, 2013, 138, 1053–1059

observed utilising a gold electrode in the accessible voltam-metric window (see ESI 1†).

We next explored the electrochemical oxidation of atropine(1 mM) as a function of pH using the edge plane pyrolyticgraphite electrode. No voltammetric waves were observed untilthe onset of pH 7 with a voltammetric peak at �+0.99 V andupon increasing the pH to more alkaline conditions resulted inthe wave shiing to less positive potentials. Through the use ofeqn (1):

Ep ¼ E0p � 2:303

mRT

nFpH (1)

where m is the number of protons, n is the number of electronsinvolved in the electrochemical mechanism, Ep is the electrodepotential and E0p is the standard electrode potential, a plot ofpeak potential, Ep, as a function of pH (ESI 2†) was found toproduce a linear response over the pH of 7 to 10 with morealkaline pH values producing a deviation from linearity. Usingthe linear range, a line of best t produced a gradient of 117 mVindicating that the electrochemical mechanism involves thetransfer of two protons and one electron (via eqn (1) at 298 K,gradient�118 mV). We note that the pKa of atropine is reportedto be 9.85 within the literature21 which is in agreement with thepH response observed above. Next, aer determining that theoptimum experimental pH for the oxidation of atropine usingthe edge plane pyrolytic graphite electrode was that of pH 10,the effect of varying the scan rate was studied as depicted inFig. 2. Scan rates over the range 5 to 400 mV s�1 were exploredwhich revealed a linear response (IP/mA ¼ 630.10 mA/(V s�1)1/2 +19.07 mA, R2 ¼ 0.99) of the peak current (IP) as a function of thesquare root of the scan rate (y) indicating a diffusion controlledelectrochemical process.

Although a desirable voltammetric trace was obtained usingthe edge plane pyrolytic graphite electrode (see Fig. 1) thedecision was made to utilise screen printed graphite electrodesdue to their ease of use and alleviation of the requirement forcleaning and polishing prior to use, whilst still offering

This journal is ª The Royal Society of Chemistry 2013

Fig. 2 The effect of voltammetric scan rate (5–400 mV s�1) on the oxidation of 1mM atropine in a pH 10 buffer solution recorded at an edge plane pyrolyticgraphite electrode.

Paper Analyst

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

behaviour akin to the edge plane pyrolytic graphite electrode(E(SPE)p ¼ �+0.82 V (vs. SCE)). Scan rate studies were undertakenusing the screen printed graphite electrode for 1 mM atropinein a pH 10 buffer. Scan rates over the range 5 to 400 mV s�1 wereexplored which revealed a linear response (IP/mA ¼ 78.90 mA/(V s�1)1/2 + 4.30 mA, R2 ¼ 0.99) of the peak current (IP) as afunction of the square root of the scan rate (y) indicating, onceagain, as was observed when utilising the edge plane pyrolyticgraphite electrode, a diffusion controlled electrochemicalprocess. The inter-reproducibility of the screen printed graphitesensors were evaluated using ve separate new sensors at a xed(1 mM) atropine concentration in a pH 10 buffer which wasfound to exhibit a % Relative Standard Deviation of 4.54%highlighting their excellent reproducibility as electrochemicalsensors.

In order to further hone the analytical procedure with theaim of allowing for the most optimised experimental parame-ters for the sensing of atropine, the potential utilisation ofsurfactants was explored. Inspired by the work of Pitre and co-workers11 who have reported upon an electrochemical methodfor the determination of atropine based on the enhancementeffect of the anionic surfactant sodium dodecyl benzenesulfonate which allows for a shi in the oxidation potential ofatropine to a much more facile potential of �+0.58 V, weendeavoured to determine the potential benecial use ofanionic, cationic and non-ionic surfactants in the sensing ofatropine. The surfactants explored were: sodium cholate,sodium dodecyl sulfate, Triton X-100 and tetraethylammoniumperchlorate with the effect of different surface concentrationsdrop-coated upon the screen printed graphite electrodesworking area prior to analysis. As depicted in Fig. 3, a range ofconcentrations were utilised for each of the surfactants with theeffect upon the voltammetric peak current for the oxidation of1 mM atropine in a pH 10 buffer being recorded. As is clearupon inspection of each of the plots depicted in Fig. 3, althoughvarying degrees of improvement are clear from the introductionand increasing concentration of surfactants, serious

This journal is ª The Royal Society of Chemistry 2013

limitations are evident when assessing the reproducibility ofthe techniques. Note, above a concentration of 46 mM for thesurfactant sodium cholate there is an apparent reduction in theobserved peak current with further increases in the sodiumcholate concentration seen to result in a steady reduction of thepeak current. Efforts were also made to understand the effect ofdifferent surfactants upon the observed peak potential for theoxidation of atropine. Shown in Fig. 4 is the effect of thesurfactants upon the voltammetric peak potential. Of the foursurfactants utilised, only Triton X-100 was seen to offer afavourable improvement in the oxidation potential for atro-pine, that is, a reduction in the overpotential to a less electro-positive potential. It is however critical to note that a reductionin the oxidation potential by only�50mV is possible. Evidently,the use of surfactants offers extremely limited improvements inthe oxidation potential of atropine at the screen printedgraphite electrode, but also poor reproducibility betweenexperiments as is demonstrated in Fig. 4. Clearly, Fig. 3 and 4highlight the potential pitfalls and problems associated withthe use of surfactant modied electrodes for the sensing ofatropine, particularly when attempting to develop a robustand reliable analytical protocol for the low-level sensing ofthe analyte.

Analytical application of the screen printed sensors

Upon determination that the most appropriate and reproduc-ible sensor to be used towards the analytical measurement ofatropine was the unmodied screen printed graphite elec-trodes, the range of atropine concentration that could bemeasured was explored. Fig. 5 depicts typical voltammetricproles resulting from additions of atropine made into a pH 10buffer solution over the concentration range 5 mM to 50 mMusing the screen printed graphite electrochemical sensingplatforms. As has been described earlier, a voltammetric peakfor the oxidation of atropine in pH 10 buffer is clear at apotential of �+0.82 V (vs. SCE), as shown in Fig. 5. Analysis ofthe peak current as a function of concentration as depicted inFig. 5 (inset) reveals a linear response over the range 5 to 20 mM(IP/mA ¼ 2.10 � 10�2 mA mM�1 + 3.27 mA; R2 ¼ 0.98; N ¼ 6) aerwhich a deviation from linearity is observed with an apparentplateauing effect of the resulting peak current and reducedreproducibility, as is highlighted through the error bars shownin Fig. 5 (inset); a limit of detection (based on three sigma)corresponding to 3.9 (�0.5) mM is found to be possible. Thisdetection limit is not as low as that reported using the tech-niques detailed in the introduction but clearly are “gold stan-dard” techniques and as noted in the introduction, a portable,economical and analytical useful sensor for atropine sensing isrequired. We note that there is only one other electrochemicalreport of sensing atropine which utilised uncharacterisedsurfactant modied multi-walled carbon nanotube paste elec-trodes. Using a two-minute mass transport enhanced “accu-mulation time”, a limit of detection of 6.4� 10�10 M is reportedto be feasible. This detection limit is obviously lower thanreported here due to the conditions employed. However, the useof screen printed electrodes is more suitable for the nal

Analyst, 2013, 138, 1053–1059 | 1055

Fig. 3 The effect of different surfactants upon the voltammetric peak current observed for the oxidation of 1 mM atropine in a pH 10 buffer. (A) Sodium cholate; (B)sodium dodecyl sulfate; (C) Triton X-100; (D) tetraethylammonium perchlorate.

Analyst Paper

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

application and the analytical performance in a real sample isnext considered.

To impart further understanding about the potential appli-cation of the analytical method towards the detection of atro-pine within a ‘true’ sample, that is, one likely to be encounteredwithin forensic applications such as the case of Agutter, asample of tonic water was utilised. When encountering, orsimulating ‘true’ samples, it is of key importance to determinethe potential effects of interference resulting from the presenceof known electroactive compounds likely encountered withinsuch a sample. Both caffeine and ascorbic acid are commonlyfound in drink samples and were therefore utilised to deter-mine their possible interference within the described electro-analytical protocol. ESI 3† depicts the voltammetric prolesobserved at a xed concentration (250 mM) of atropine over arange of ascorbic acid (ESI 3A†) and caffeine (ESI 3B†) concen-trations. In the case of caffeine no voltammetric peaks wereobserved and hence appears to have no effect upon the sensingof atropine at this chosen pH. In the case of ascorbic acid, thevoltammetric peak is observed to grow with concentrations asexpected which is resolved from the electrochemical oxidation

1056 | Analyst, 2013, 138, 1053–1059

wave of atropine. At higher concentrations, the baseline appearsto start to affect that of the atropine and depending on theconcentration of ascorbic acid in the real samples, an interfer-ence issue may occur. We next turn to exploring whether thiselectroanalytical protocol might be useful for atropine sensingin real drink samples.

Next, tonic water was rst prepared as described within theExperimental section with the sensing of atropine attempted.However, the inclusion of quinine within the tonic water samplewas found to cause severe problems for the sensing of atropinewhen utilising the electrochemical protocol. As is depicted inFig. 6, the voltammetric response in the absence of atropinegives rise to an electrochemical oxidation peak at the samepotential as that observed for atropine (see above). Sincequinine is reported to be electroactive22 the observed voltam-metric peak is likely due to the electroactivity of quinine withinthe tonic water sample. Additions of atropine into the tonicwater sample, buffered to pH 10 prior to analysis, wereattempted, though no further voltammetric peaks wereobserved. Such an outcome would however be expected as theoxidation peak realised within the tonic water sample was of a

This journal is ª The Royal Society of Chemistry 2013

Fig. 4 The effect of different surfactants upon the voltammetric peak potential observed for the oxidation of 1 mM atropine in a pH 10 buffer. (A) Sodium cholate; (B)sodium dodecyl sulfate; (C) Triton X-100; (D) tetraethylammonium perchlorate.

Fig. 5 Cyclic voltammetric responses recorded at a screen printed graphiteelectrochemical sensing platform from additions of atropine (5 to 50 mM) into apH 10 buffer solution. Inset: a typical corresponding calibration plot. All scans vs.SCE at 50 mV s�1.

This journal is ª The Royal Society of Chemistry 2013

Paper Analyst

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

greater magnitude (peak current) than that upon the addition ofatropine to ‘ideal’ buffer solutions; it is likely that the quininepeak present within the tonic water solution masked that ofatropine. The use of surfactants was also explored in the hopethat the two signals could be resolved, but unfortunately, thiswas not found to be possible. Thus it is clear why there are noelectrochemical reports of sensing atropine in real drinksamples.

Upon the realisation that the electrochemical monitoring ofatropine within tonic water samples was not viable, attemptswere made to explore the sensing of atropine in a further ‘true’analytical sample likely to be encountered. Still inspired by thecase of Agutter who, as described in the Introduction, usedatropine as a deadly poison in an attempt to murder his wife,4

we have determined the viability of the sensing of atropinewithin a diet Coca-Cola buffered to the optimised pH of 10(prepared as dened within the Experimental section) whichcould conceivably be used to mask the bitterness of atropine.The response in the absence and presence of atropine wasexplored using the same experimental parameters andconcentration range (5 to 50 mM) as utilised under ‘ideal’

Analyst, 2013, 138, 1053–1059 | 1057

Fig. 6 A typical cyclic voltammetric response recorded at a screen printedgraphite electrochemical sensing platform in a tonic water solution in the absenceof atropine, buffered to pH 10. Scan rate: 50 mV s�1.

Analyst Paper

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

conditions as is depicted in Fig. 7. Evidently, upon inspection ofthe blank voltammagrams (dotted line), no oxidative or reduc-tion voltammetric peaks are observed, whilst the addition ofatropine results in the formation of a clear oxidation peak at�+0.82 V (vs. SCE). Scrutiny of the voltammograms depicted inFig. 7 reveal an apparent increase in voltammetric peak currentupon the addition of atropine into the diet Coca-Cola samplewith no voltammetric peaks being observed within the blankdiet Coca-Cola sample (Fig. 7, dotted line). This belief isconrmed, as demonstrated in Fig. 7 (inset), through a plot ofvoltammetric peak current as a function of concentration whichreveals a linear response over the entire analytical range 5 to50 mM (IP/mA ¼ 1.07 � 10�2 mA mM�1 + 20.4 mA; R2 ¼ 0.99; N ¼10). Furthermore, the reproducibility of the screen printedgraphite sensor within the diet Coca-Cola buffer is highlighted

Fig. 7 Cyclic voltammetric responses recorded at a screen printed graphiteelectrochemical sensing platform from additions of atropine (5 to 50 mM) intodiluted diet Coca-Cola buffered to pH 10. Inset: a typical corresponding calibra-tion plot. All scans vs. SCE at 50 mV s�1.

1058 | Analyst, 2013, 138, 1053–1059

in Fig. 7 (inset) through the inclusion of error bars. A limit ofdetection (based on three sigma) for atropine in the diet Coca-Cola buffer was found to correspond to 18.4 (�0.2) mM. While adeviation in comparison of the ‘ideal’ and ‘true’ analyticalsamples evident (viz. gradients) is evident, the linear rangeappears to be analytically useful.

Returning to the original case of Agutter (see Introduction) itwas determined via forensic scientists that Mrs Agutter's ginand tonic had been spiked with a concentration correspondingto �1 mM atropine, while in a spiked bottle of tonic water,which was placed onto the supermarket shelves, was found tocorrespond to �0.35 mM.1 Assuming that someone mightrecreate the case of Agutter, both concentration levels areassessable using the electrochemical protocol described herein,of course following dilution with a suitable buffer solution. Notethat an average fatal dose of atropine is 100 milligrams and thusMrs Agutter would have been required to drink �330 mL of themixture provided by her husband to receive such a dose.1

However, in her fortune, when the symptoms hit Mrs Agutter,that is, agonising pain in the throat, thirst, nausea, dizzinessand visual hallucinations she ceased drinking and therefore didnot receive the required, nor intended, lethal dose, thus higherconcentrations would be necessary for the successful murder;such concentrations could be determined utilising this sug-gested analytical protocol.

Conclusions

We have demonstrated for the rst time the successful elec-trochemical oxidation of atropine utilising an unmodiedscreen printed graphite sensor. The ease of fabrication, massproduction and importantly, low cost of the sensor which allowsfor excellent reproducibility for the sensing of the analyteprovides a real possibility for the development of a ‘real-world’electrochemical sensing device for the monitoring of atropinelevels. Interestingly we also note that little benet is yieldedthrough the incorporation or utilisation of numerous surfac-tants, with such modications of the methodology resulting indramatically diminished reproducibility and in some instancesimpedance of the sensing through blocking of the screenprinted graphite sensor. Further to this, the limitation of theprotocol is evident when attempting to sense atropine withintonic water samples which contain quinine which is electro-chemical active23 and is found to interfere strongly with that ofatropine. However, the protocol has been shown to besuccessfully utilised for the possible sensing of atropine indiluted diet Coca-Cola, a sample which might be used to maskthe bittiness of atropine when the molecule of murder atropineis used for poisoning.

References

1 M. R. Lee, J. Roy. Coll. Phys. Edinb., 2007, 37, 77.2 P. A. Steenkamp, N. M. Hardinga, F. R. van Heerden andB.-E. van Wyk, Forensic Sci. Int., 2004, 256, 31.

3 R. Boyd, N. Nichol, J. P. Wyatt and K. Little, Eur. J. Emerg.Med., 1997, 4, 172.

This journal is ª The Royal Society of Chemistry 2013

Paper Analyst

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 10

Mar

ch 2

013

Publ

ishe

d on

04

Janu

ary

2013

on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/C

2AN

3645

0FView Article Online

4 J. Emsley,Molecules of Murder: Criminal Molecules and ClassicCases, The Royal Society of Chemistry, Cambridge, 2008.

5 The Guardian, Supermarket Poisoner Lectures UniversityStudents on Ethics, 2004, http://www.guardian.co.uk/uk/2004/mar/2011/highereducation.supermarkets.

6 Daily Record, A Gin and Tonic Laced With DeadlyNightshade.Who Was Trying to Poison The Capital?, 2007,http://www.dailyrecord.co.uk/news/scottish-news/a-gin-and-tonic-laced-with-deadly-nightshadewho-961080.

7 British Broadcasting Corporation News, Prisoner Employed asEthics Tutor, 2004, http://news.bbc.co.uk/1/hi/education/3497860.stm.

8 D. Rancic and A. Spasic, Toxicol. Lett., 2009, 189, S234.9 A. Namera, M. Yashiki, Y. Hirose, S. Yamaji, T. Tani andT. Kojima, Forensic Sci. Int., 2002, 130, 34.

10 J. P. Metters, R. O. Kadara and C. E. Banks, Analyst, 2011,136, 1067.

11 R. A. Dar, P. K. Brahman, S. Tiwari and K. S. Pitre, ColloidsSurf., B, 2012, 91, 10.

12 G. A. E. Mostafa and M. N. Abbas, Instrum. Sci. Technol.,2008, 36, 209.

This journal is ª The Royal Society of Chemistry 2013

13 N. Bibire, G. Tantaru, V. Dorneanu, M. Stan and M. Apostu,Rev. Med.–Chir. Soc. Med. Nat. Iasi, 2003, 107, 218.

14 J. Li, Y. Chun and H. Ju, Electroanalysis, 2007, 19, 1569.15 B. Yuan, C. Zheng, H. Teng and T. You, J. Chromatogr., A,

2010, 1217, 171.16 R. O. Kadara, N. Jenkinson, B. Li, K. H. Church and

C. E. Banks, Electrochem. Commun., 2008, 10, 1517.17 P. M. Hallam, D. K. Kampouris, R. O. Kadara and

C. E. Banks, Analyst, 2010, 135, 1947.18 M. Gomez-Mingot, J. Iniesta, V. Montiel, R. O. Kadara and

C. E. Banks, Sens. Actuators, B, 2011, 155, 831.19 M. Gomez-Mingot, J. Iniesta, V. Montiel, R. O. Kadara and

C. E. Banks, Analyst, 2011, 13, 2146.20 A. V. Kolliopolous, J. P. Metters and C. E. Banks, Anal.

Methods, 2013, 5, DOI: 10.1039/c2ay26041g.21 W. D. Dettbarn, E. Heilbronn, F. C. G. Hoskin and R. Kitz,

Neuropharmacology, 1972, 11, 727.22 S. Awasthi, A. Srivastava and M. L. Singla, Synth. Met., 2011,

5, 1707.23 R. A. Dar, P. K. Brahman, S. Tiwari and K. S. Pitre, Colloids

Surf., B, 2012, 98, 72.

Analyst, 2013, 138, 1053–1059 | 1059