This article was downloaded by: [Universitat Politècnica de València]On: 26 October 2014, At: 11:13Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK

Analytical LettersPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/lanl20

Micelle EnhancedSpectrofluorimetricDetermination of NorfloxacinUsing Terbium as FluorescentProbeZuyun Huang a , Ruxiu Cai a , Ke Zhang a , HoupingHuang a & Yune Zeng aa Department of Chemistry , Wuhan University ,Wuhan, 430072, P.R. ChinaPublished online: 22 Aug 2006.

To cite this article: Zuyun Huang , Ruxiu Cai , Ke Zhang , Houping Huang & YuneZeng (1997) Micelle Enhanced Spectrofluorimetric Determination of NorfloxacinUsing Terbium as Fluorescent Probe, Analytical Letters, 30:8, 1531-1539, DOI:10.1080/00032719708001673

To link to this article: http://dx.doi.org/10.1080/00032719708001673

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all theinformation (the “Content”) contained in the publications on our platform.However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness,or suitability for any purpose of the Content. Any opinions and viewsexpressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of theContent should not be relied upon and should be independently verified withprimary sources of information. Taylor and Francis shall not be liable for anylosses, actions, claims, proceedings, demands, costs, expenses, damages,and other liabilities whatsoever or howsoever caused arising directly or

indirectly in connection with, in relation to or arising out of the use of theContent.

This article may be used for research, teaching, and private study purposes.Any substantial or systematic reproduction, redistribution, reselling, loan,sub-licensing, systematic supply, or distribution in any form to anyone isexpressly forbidden. Terms & Conditions of access and use can be found athttp://www.tandfonline.com/page/terms-and-conditions

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

ANALYTICAL LETTERS, 30(8), 1531-1539 (1997)

MICELLE ENHANCED SPECTROFLUORIMETRIC

DETERMINATION OF NORFLOXACIN USING TERBIUM

AS FLUORESCENT PROBE

KEY WORDS: Norfloxacin, Terbium(lIl), fluorescent probe

Zuyun Huang, Ruxiu Cai, Ke Zhang, Houping Huang, Yune Zeng

Department of Chemistry,Wuhan University , Wuhan,430072, P.R. China

ABSTRACT

Terbium(II1) forms highly fluorescent complex with norfloxacin. The

presence of surfactant can enhance greatly fluorescence intensity. In this paper, the

fluorescence characteristics of complex in presence of surfactant has been

investigated. It was found that norfloxacin could form stable complex with terbium

in the pH 6.5-8.5 media. The fluorescence intensity of complex in SLS media is

three folds more than complex itself. A new micelle enhancement

spectrofluorimetry for the determination of norfloxacin has been developed .The

detection limit of proposed method is 0.017pg/ml. It has been satisfactory for the

determination of trace norfloxacin in serum with 95.2% -10 1.2% recoveries.

1531

Copyright 0 1997 by Marcel Dekker, Inc.

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

1532 HUANG ET AL.

INTRODlJCTION

Norfloxacin[ 1 -ethyl-6-fluoro- I ,4-dihydro-4-oxo-7-( piperazin- 1 -y l)quinoline-

3-carboxylic acid] is the third representative of antibacterial medicine. namely

quinolone group, used extensively in the clinical treatment with higher potential and

a broad antibacterial spectrum, lower side effects. It killed bacteria through

inhibiting cell DNA-gyrase and prohibiting DNA-replication. I t is thus chosen

commonly as antibacterial medicine in the treatment of urinaq-tract infections.

gonorrhea and bacterial enteritis'. Previous literature have reported some method

for the determination of norfloxacin(NFX). such as HPLC. spectrophotonietiy.

microbioassay etc.2-S. However. most of them are based on intrinsic florescence.

The sensitivity of method is low. time-consuming and more back~round- in te r~~r in~ .

Recently, D. Perez-Bendito6 reported a method for deteiinination of

norfloxacin. which is based on a suitability of stopped-flow technique with

lanthanide-sensitized fluorescence for the determination of nalidixic acid and

norfloxacin. However, sensitivity of the method is still low. In this paper. we

combined h e advantages of micelle enhancement and lanthanide fluorescent probe.

A simple method with improved sensitivity and stability is proposed. The method

is based on terbium(lI1) forming a lughly fluorescent complex with norfloxacin. The

presence of surfactants (SLS) can enhance greatly the fluorescence of the complex.

The detection limit of the proposed method is 0 . 0 ~ 7 p ~ i i i l . Linear range is 0.05-

lpdml, the analybcal recoveries are between 95.2%-10 1.2%. The method has been

successfully applied to determine trace norfloxacin i n serum.

EXPERIMENTAL

Apparatus

All fluorescence intensity measurements were made on a SMF-25

specwofluorimeter (Kontron Instrument) with 1.Ocm quartz cells. Values of pH were

measured with a model of digital display pH meter ( Wuhan precision Insh-urnent

Corp., China).

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

TERBIUM AS FLUORESCENT PROBE 1533

Reagents

Analytic-reagent grade chemicals were used. solutions were prepared in

doubly distilled water.

The lanthanide oxides were obtained from Yuelong Chemical Corp.(Shanghai,

China) in purity of more than 99.99%. Stock solutions of the lanthanide ion( Img/ml

Tb,O,) were prepared by dissolving known amounts of the appropriate rare earth

oxide in hydrochloric acid.

Norfloxacin (NFX) was obtained from Medicine and Bioproducts Test

Institute of Health Ministry. Stock solution of lmg/ml NFX solution was prepared

in 0. Imol/L sodium hydroxide and stored in a refrigerator (4OC). Standard solutions

were prepared fresh daily by diluting the stock solution. The sodium lauryl

sulfonate was obtained from Beijing Chemical Corp.( 1 . 0 ~ lO-*mol/L). The buffer

solution used was 0.2moVL Tris-HC1. The pH values were adjusted to 8 with

0.2moVL hydrochloric acid. A11 water used was doubly distilled water from quartz

vessels.

Procedure

To a lOml test tube, known amounts of NFX, Tb3+ standard solution, SLS

(1 x 10-2mol/L), 0.2mol/L Tris-HC1 buffer solution were added sequentially. The

volume was diluted to l h l with doubly distilled water, mixed well, and allowed

to stand for 5min at room temperature. The relative fluorescence intensity was

measured by setting the excitation and emission wavelengths at 325 MI and 545 tun

respectively.

RESULTS AND DISCUSSION

P c e spectrum

Fig. 1 shows the typical fluorescence spectrum of NFX,Tb3+-NFX,Tb3+-NFX-

SLS system at pH 8.0 obtained under experimental condition. The excitation of

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

1534 HUANG ET AL.

A.excitation spectra

Fig. 1.

0 Wavelength (nm)

B. emission spectra

Fluorescence spectra

( I ) 0.5pg/ml NFX(pH=8.0)

(2) 0.5pg/ml NFX+4.92* 10-smol/LTb3+(pH=8.0)

( 3 ) 0.5 pdml NFX+4.92 x I 0-'mol/LTb3++9x 1 O4mol/LSLS(pH=8.0)

NFX is at 280nm and 332nm, its emission peak is 410nm. The excitation peak of

Tb3+-NFX complex moves to long wavelengths of 288nm and 332nm. The emission peaks of complex at 49Onm, 545nm, 590nm and 625nm are attributed

to the sD,-7D,(n=6,5,4,3) transition of Terbium. The most intense peaks are the

5D,-7D, transition at 49Onm and the sD,-7Ds transition at 545nm. Its luminescent

mechanism belongs to L-M; the emission peak(4lOnm) of NFX decreases. In the

presence of surfactant, the fluorescence intensity of the complex is enhanced

greatly,but the position of peak of the complex doesn't change.

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

TERBIUM AS FLUORESCENT PROBE 1535

Effect of Tb3+ concentration

Lanthanide ions. especially europium(ll1) and terbium (111) , emit the energy

as narrow-banded line-type fluorescence spectrum with long Stockes shifts(over

250nm) and exceptionally long fluorescence decay times(0. I-lms). They are widely

used as fluorescence probe. In tlus work, the effect of terbium(lI1) concentration on

fluorescence intensity of system was studied. It was found that a maximum and

stable fluorescence intensity was obtained between 3.280~10-"-4.373 x 1 O-'mol/L.

Effect of surfactants

In the presence of surfactants, equilibrium, kinetic and spectral properties can

be modified and this has been used to improve the characteristics of analytical

procedures. The use of surfactant media can also enhance fluorescence intensity in

the spectra of drug molecules. Perhaps due to the formation of a stable mixed-

ligands complex above(CMC) critical micelle concentration, the solubility of

complex increases greatly. Hence the fluorescence intensity is enhanced greatly.

Fig.2. shows that the fluorescent intensity of system increases dramatically below

8 . 0 ~ 10-4mol/L of SLS, then reaches maximum at 9.0. IO-'mol/L SLS.(see Fig.2.)

Effect of DH and species of buffer solutions

The influence of pH on fluorescence intensity was investigated in the NFX

and NFX-Tb3+ system (see Fig.3). It was well known that the NFX molecular is

monoatomic acid with emitting intensive fluorescence at the acid

medium@H=l-3.5). The fluorescence emission body is the state of molecular in the

acidic media, whereas the ionic state is the weak fluorescent emission body in basic

media. Hence the fluorescence intensity Tb-NFX complex reaches maximum at pH

8.0. The optimum pH range is 7.0-8.5.

The fluorescence intensity of Tb3+-NFX systems was measured at the pH 8.0

with some species of the buffer solution. The results obtained are shown in Table2.

The experiments show that the 0.2M Tris-HCI buffer solution (pH=8.0) is best.

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

1536 HUANG ET AL.

Fig.2.Effect of SLS on fluorescence intensity

0.5pg/ml NFX+4.92 1 0-smol/LTb3+(pH=8.0)

Fig.3. Effect of pH on the fluorescence intensities of NFX and Tb3+-NFX

a: [NFX]= 0.5pg’ml he, /h,,,=332/440nm

b: 0.5 pg/ml NFX+4.92 x 1 O-smol/LTb3+ hey /h,,,=3 32/545nm

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

TERBIUM AS FLUORESCENT PROBE 1537

Table 1. Surfactants effect

surfactant no Bnj35( 1%) TX-100( 1%) CTAB( 1 x I04M) TPC*(0.2%) SDBS(O.2%) SLS( I x 10"M) If 27.3 37.3 33.5 25 .8 17.8 51.5 72.5

'Tetradecyl pyridine chloride

Table 3. The effect of various substances on the fluorescence intensity

species Ca2'(Mg2') Zn2+ Fe3+ cu2+ v c ............................................................................................... concentration(mol/l) 1 x lo" 1 . 2 ~ 1 . 6 ~ 5 . 5 ~ lo-* I x lo-'

Table 4. Determination of NFX in serum samples

sample concentration of NFX added in serum average value recovery h i d mu (Pg/mu (%)

1 0.800 0.762 95.3

2 0.500 0.495 99.0

3 0.300 0.298 99.2

4

5

0.100

0.0750

0.1013 101.3

0.0759 101.2

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

1538 HUANG ET AL.

The stability of complex

The experiment shows that the fluorescence intensity of the system reaches a

maximum for ~ m i n at room temperature containing I x IO-’~OI/L, I x 1u6mol/L

NFX, and the complex stablizes for 24h.

Effect of interference SD . ecies in body

Table 3 shows the infuence of some metal ions and Vc in biological body

on fluorescence intensity. The following amounts of substances don’t interfere in

the determination for the concentration of 4 . 9 2 0 ~ 10-5mol/LTb3+ and O.l&ml

NFX:

Determination of NFX in s u

Under the experimental conditions, The fluorescence intensity with the

concentration of NFX is a linear relation in the range 0.05-lpg/ml,the

determination results deviated slightly from a linear relationship at high

concentration.The detection limit is O.O17pg/ml. The new method was applied

successfully to determine NFX in serum by standard addition method (see Table 4).

ACKNOWLEDGEMENTS

The authors gratefully acknowedge financial support from the National

Science Foundation of China.

REFERENCES

1. L.F. Wu, J.P.Zhang; Handbook of Import Medicine; Chinese Medical

Science and Technology Press, Beijing, 100- 10 1 ( 199 1).

G.Y.Zhao, H.Z.Fan, J.H.Pan, Chinese J. Pharm. Anal., 15(5)48-60 (1995). 2.

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014

TERBIUM AS FLUORESCENT PROBE 1539

3. J.R.Zhang, H.Pang, X.Y.Liu, Sh.J.Pan, H.S.Wang, Chines J . Pharm. Anal..

30(7)428-429 (1995).

4.

5 .

J. Georges, S. Ghazarian, Anal. Chim. Acta. 276:401-409 (1993).

P. Izquierdo, A. Gomez-hens, D. Perez-bendito. Anal. Chim. Acta. 292: 137-

139 (1994).

S. Panadero, A. Gomez-hens, D. Perez-bendito, Anal. Chim. Acta. 303:39-

45 (1995).

6 .

Received: November 1. 1996 Accepted: March 10. 1997

Dow

nloa

ded

by [

Uni

vers

itat P

olitè

cnic

a de

Val

ènci

a] a

t 11:

13 2

6 O

ctob

er 2

014