olaquindox was 1 − a gL µ 2011 Society of Chemical Industry This method can be reliable, c 1,6,7 levels were extracted and determined they would be more sensitive but require 1 − 8,9 Dongyan Zhao, b Correspondence to: Zhixiang Xu,Shandong College Agricultural University, of Taian, China. Food E-mail: [email protected] Science and Engineering, College of Food ScienceTaian, and China Engineering, Shandong Agricultural University, College of Food ScienceQingdao, China and Engineering, Qingdao Agricultural University, Much effort has been devoted to the development of analytical lid-phase extraction; high performance liquid chromatography ∗ a b over possible carcinogenic, mutagenic and photoallergenic material of olaquindox-imprinted polymer was synthesised y, and fast adsorption-desorption dynamics for olaquindox. ination with a sol–gel process. This imprinted material was methods for assessing thebased presence on of high-performance this liquid compoundultra-violet chromatography residues (HPLC) (UV) with detection. animal feeds and foods are required for thehealth. assurance of consumer while itprocedure, has time several consumption,chromatography–mass potential and spectrometry (GC-MS) insufficient drawbacks, and LC sensitivity.MS/MS coupled including (LC-MS/MS) to Gas for tedious thehave detection been of reported; the olaquindox in feeds , rapid and sensitive analytical method for determination of microscopy, and static and kinetic adsorption experiments, and h accelerants, is usually used as a feed additive in livestock In 4 , the RSD for five replicate extractions of 50 1 − Haihua Chen, a Other study ∗ 2 a However, with the incorrect 1 For these reasons, accurate and 5 Xuguang Qiao, a,b 3) for olaquindox was 68.0 ng L and Zhixiang Xu = : 2378–2385 www.soci.org a N -2-hydroxyethylcarbamonyl)-3-methyl-quino- 91 / N S Furthermore, olaquindox can accumulate in rats 3 2011; -dioxide), as one of the most known members of molecular imprinting; olaquindox; molecularly imprinted so 4 N ,

1 N

2011 Society of Chemical Industry c reliable analytical methods for the determination of olaquindox in quinoxaline-1,4-dioxides (Fig. 1) and the antimicrobialcelerants, growth is ac- usually used as feedto additives in improve livestock production feed efficiency,rial control enteritis swine in dysentery youngincrease and swine to the bacte- prevent rate diseases of in weight animals gain. and J Sci Food Agric effects of olaquindox onolaquindox animals, is crucial the and development necessary. of a simple RESULTS: In this paper,in a aqueous novel solution and bycharacterised hydrophilic by a Fourier functionalised surface transform infrared, molecular scanningresults electron imprinting showed in that comb itApplying had the good prepared recognition material and asand sorbent, selective analysis a abilit method of of olaquindoxdetection molecularly limit imprinted residues ( solid-phase in extraction feeds (MISPE) for coupled separation with HPLC was presented. Under the selected MISPE condition, the INTRODUCTION Olaquindox (2-( production to improve feed efficiency. Due to health concerns

Abstract BACKGROUND: Olaquindox, one of the antimicrobial growt olaquindox residues in chick feeds Yue Zhang, chromatography for analysis of trace Jiaming Song, combined with high-performance liquid Molecularly imprinted solid-phase extraction (wileyonlinelibrary.com) DOI 10.1002/jsfa.4471 Research Article Received: 6 December 2010 Revised: 4 March 2011 Accepted: 5 April 2011 Published online in Wiley Online Library: 14 June 2011 by the developed method, with recoveries ranging from 90% to 96%. CONCLUSION: This method was applied forand enrichment repeatability. and This analysis study will of provide olaquindox a in sensitive animal and feed fast samples method with for good the accuracy monitoring of olaquindox residues in foods. Keywords: use of olaquindox, severalous problems study have indicated been that exposed. thefarm Previ- may excessive have use adverse of effects on olaquindox the in environment. fish and mice and induce strong toxic reactions, such as mortality. the European Union, due to health concerns over possiblegenic, carcino- mutagenic and photoallergenic effectson animals, of its the use was olaquindox prohibited inotic animal from feeds the as beginning a of feed 1998. antibi- showed that olaquindox could destroytem of antioxidant animals. defence sys- 9.8%. The blank chick feed samples spiked with olaquindox at 0.0025 and 0.010 mg g xaline-

2378 2379 )and 1 column − 18 . Class-vp software was 1 − wileyonlinelibrary.com/jsfa C. After polymerisation was -aminopropyltriethoxysilane ◦ γ L and detection was at 372 nm. SPE column (200 mg/3 mL) was obtained µ 18 O OH 2 N O O N 250 mm, Agela Technology, Newark, Delaware, USA) at CH × 2 The imprinted polymer was prepared as follows: 1.5 g 25 . The HPLC system consisted of two LC-10ATVP pumps and a Shi- 3 a mobile phase flow rate of 0.8 mL min (4.6 mm complete, the product was filtered, washed with methanol and of olaquindox was dissolved6 in mL 30 of mL APTES ofand stirring DDW, for 10 and mL 20 mixed min, of thenmixture with TEOS 0.5 was g were mixed activated added. silica with gel After 4 mL stirring of for acetic 10 min, acid the (0.1 mol L madzu SPD-10AVP ultraviolet detector (Shimadzu). All separations wereachievedonananalyticalreversed-phaseThermoC from Phenomenex (Torrance, California, USA). used to acquire and processThe spectral mobile and phase chromatographic was data. methanol/watervolume injected (85 was : 15, 15 v/v). The sample Preparation of molecularly imprinted polymers The method toet al activate the silica gel followed that of Han EXPERIMENTAL Chemicals Olaquindox, mequindox andthe quinocetone Institute were for the obtained Controlculture from of (Beijing, Agrochemicals China). of Ministry Silica of gelChemical Agri- (80–100 Co., mesh, Qingdao, Qingdao China) Ocean rial. Tetraethoxysilicane was (TEOS) and used as(APTES) were purchased the from WD support Silicone Co., mate- LtdThe (Wuhan, HPLC China). grade methanol andTianjin acetonitrile yongda Chemical were Co. (Tianjin, purchased China). from All thewere other reagents analytical grade. Doublythroughout deionised the water study. (DDW) was used Apparatus and HPLC analysis For determination of the adsorption capacity of theand new imprinted non-imprinted polymer,(Mulgrave, Victoria, a Australia) Caryscanning was electron 50-Bio used. microscope UV A (Shimadzu,US-501 horizontal spectrometer Kytoto, 20.0 shaker kV (Jintian, Japan) Beijing, on China) and werestudy. used The a a Strata in Scx this SS-35 C then was incubated for 10 h at 50 CONHCH CH 14 13 N N O O Their use However, Olaquindox 18 11 2011 Society of Chemical Industry 3 bonded silica. c

CH

3 18 CH O N N O O and cannot be widely used for Mequindox Quinocetone biomimetic sensors. 10 The applications of MIPs have 16,17 12 : 2378–2385 19–25 91 2011; enzymes mimics, 15 Chemical structures of olaquindox, quinocetone and mequindox. The aim of this study was to synthesize a highly selective Among the approaches applied one of the most interesting Determination of olaquindox in chick feeds www.soci.org routine analytical purposes. Furthermore, theof low olaquindox concentration combined withimplicated the samples complexity make of itsmost the sophisticated detection instrumentation. matrix difficult, In in evenof order with to olaquindox, control the developing thethe a use extraction simple and analysis and offood effective olaquindox origin is residues method of in for particular animalsthe significance of and necessary necessity. levels To of achieve step sensitivity, is an needed. extraction Solid-phase extraction andtechnique (SPE) separation is and a well has established extraction (LLE) been in biological used samples prior to to analysis. substitute for liquid–liquid olaquindox molecularly imprinted material byimprinting surface molecular in combinationwhich with can a be used sol–gelanalytical as technique for process SPE monitoring sorbent. technique, olaquindoxmolecularly A in chick imprinted convenient feeds solid-phase and by extraction effective in (MISPE) combination technique with HPLCaffecting system preconcentration was and established. separationdiscussed The of the factors in analytes detail, were evaluated. and the applicability of this method was It can also concentrate otherwhich may compounds interfere with present the analysis. in The the preparationsorbent of for matrix, selective SPE is crucial. and promising method is using molecular imprintingThe technology. resulting molecularlypossess imprinted high selectivity polymers and specificity for (MIPs), template molecules, but notalso exhibit only far greater physiochemicalin stability and harsh applicability chemical media. most of the commercial solid phase sorbent is C J Sci Food Agric immunoassays, microreactors, andcatalysis, antibody binding mimics, relatively expensive instruments, Figure 1. been reported in many fields, such as affinity separation, as sorbent material for SPE isapplications the of MIPs. most interesting and important . et al : 2378–2385 91 olaquindox was 1 − 2011; ) was calculated. Uptake Q level with novel imprinted 1 3 − CH J Sci Food Agric 2 for 20 min. The supernatants were 3 3 3 g CH CH CH × 2 2 2 OCH 3 3 CH CH Si OCH OCH OCH 2 2 2 Si OCH OCH CH 2 2 CH 2 - HCH 6 2 CH PF H H N + CHC Selective recognition studies were performed by adsorbing O H 2 Extraction H H N for 4 h at room temperature with aarated horizontal centrifugally shaker at and 4320 then sep- olaquindox and structurallyand related quinocetone compounds at of the mequindox 100 mg L evaluated. After shaking for 5, 30,room 60, temperature, the 90, adsorption 120, capacity 180 was and determined. 240 min at polymer. The supernatants weremequindox and measured quinocetone at for 372 the and 314 unextracted nm, respectively. Procedure of MISPE combined with HPLC To evaluate the applicability offor the extraction MIP as and functionalised determination sorbent ofcoupled trace with olaquindox HPLC, in samples 200empty mg of SPE MIP cartridge.cartridge or The NIP was was firstly molecularlyfollowed packed rinsed imprinted by into loading with 100 an SPE mL 5 of (MISPE) mL standard olaquindox of solution at methanol a and DDW, measured for the unextracted olaquindox372 by nm UV and spectrometry at the adsorption capacity ( kinetics of the imprinted polymer for 100 mg L + HAC H TEOS BMIM + C ◦ )in O- 1 2 − OH 2 CH 2 www.soci.org Zhixiang Xu Cfor8h. CH ◦ 2 2011 Society of Chemical Industry c 3 3 CH CONHCH NaOH and washed printed sol–gel polymer of olaquindox. CH CONHCH 1 − Imprinted cavity N N O O N N O O HCl under magnetic stirring for 4 h to remove 1 − Preparation process of the molecularly im For comparison, a non-imprinted polymer (NIP) was also a 50 mL volumetric flask. The mixtures were mechanically shaken with DDW. After soxhlet extraction with 300 mL ofacid methanol/acetic (3 : 1, v/v) forFinally, 8 the h polymer and was then washed DDW/acetic with acidto 300 be (3 free mL : of 1, of olaquindox v/v) methanol by for for HPLC and 8 4 dried h. h under vacuum at 80 wileyonlinelibrary.com/jsfa DDW sequentially to remove the unreacted reagents and template molecules (Fig. 2), and dried in a vacuum oven at 100 Figure 2. Characterisation of molecularly imprinted polymers To investigate the adsorption and recognitionvironment, ability 20 in mg of water novel en- imprintedpolymer polymer were and equilibrated non-imprinted with 10 mL oftaining acetonitrile solution olaquindox con- at various concentrations (20–100 mg L for 12 h. synthesised in the same way as the MIP but without the template. olaquindox. The product wasethanol, isolated and by then neutralised filtration, with washed 0.1 mol with L The polymer wasof extracted 1.0 with mol L 50 mL of ethanol and 15 mL

2380 2381 g O µ 0 . indicated the 1 − indicated a C ) containing 5 1 1 10 mL of acetonitrile − − × indicated the Si–O stretch, wileyonlinelibrary.com/jsfa 1 − indicated the Si–O–Si stretch. 1 indicated the C–N stretch, the − and 20 mg L 1 1 − − indicated the N–H stretch and those 1 for 30 min, and the supernatants were − g × g of olaquindox, respectively. After incubated for 1 h, the µ The features around 1508 cm C–O stretch andolaquindox O–H has an–OH stretch, group. For respectively, thethe non-imprinted which features polymer around (b), showed 790 and that 458 cm features around 1069 cm separately weighed into a 100 mL conicalof flask, standard spiked solution with (5.0 1.0 mg mL L RESULTS AND DISCUSSION FTIR analysis of molecularly imprinted polymers and non-imprinted polymers The Fourier transformimprinted polymer infrared after extraction (FTIR)are and compared spectra non-imprinted in polymer of Fig.(a), 3. the olaquindox, For observed the features FTIR around spectra 1659 of cm the olaquindox stretch, and those around 1079 and 3421 cm and the features around 1069 cm solution for 30 min. Thecentrifuged resulting at extractions were 4320 collectedfiltered and for the MISPE procedure. and 20 spiked samples were ultrasonicated with 3 to 1 − 2011 Society of Chemical Industry c Lofthefiltrate µ to completely desorb 1 − SPE cartridges for the extraction of 18 , and the olaquindox was selectively pre- 1 − : 2378–2385 m filter membrane, and 15 µ 91 45 . 2011; FTIR spectra of (a) olaquindox, (b) non-imprinted polymer, and (c) imprinted polymer. Determination of olaquindox in chick feeds www.soci.org Sample preparation The chick feed wasin purchased July, from the 2010 animal (Shandong,developed market MISPE-HPLC China). method, of the To Taian feed checkdetermined sample to be for the free spiking of olaquindox. was accuracy Briefly, 2.0 g of of blank feed the was the olaquindox standard solution. was injected into HPLC for analysis. The peakat areas were calculated 273 nm andwere used flushed sequentially for with 5 data mL ofnext evaluation. methanol sample and DDW pre-concentration. Finally, for Under the the thiscycle condition, cartridges a of complete the MIPolaquindox and lasted for HPLC 70 min. separation For comparison, and thewas same determination procedure employed of using the the C the analytes adsorbed on the SPE microcolumn. Thefiltered effluents were with a 0 J Sci Food Agric Figure 3. flow rate of 2.0 mL min remove the impurities,methanol/DDW and (95 : then 5, v/v) eluted at 6.0 by mL min 0.3 mL portions of concentratedontothesorbent-packedcartridge.Whenthesample loading had finished, the cartridges werewith conditioned thoroughly 0.5 mL of methanol/DDW (40 : 60, v/v) at 6.0 mL min . 1 − et al : 2378–2385 respectively, 91 1 − 2011; ) -1 was determined (Fig. 7). The 1 and 0.42 mg g − J Sci Food Agric concentration, and the dynamic 1 Time (min) − C (mg L 1 − concentration of concentrations, and the 1 − MIP NIP ,1.37mgg 1 − for the imprinted polymer was obtained, which 1 − Kinetic uptake plot of the imprinted polymer. Adsorption isotherms of the imprinted and non-imprinted 0 30 60 90 120 150 180 210 240 270

0 20406080100120

9 8 7 6 5 4 3 2 1 0

8 7 6 5 4 3 2

) g (mg Q ) g (mg Q

-1 -1 Uptake kinetics of olaquindox by the imprinted polymer was In order to study the selective recognition property of the adsorption of concentrationsplotted by in Fig. the 6.of imprinted After 5.37 mg g shaking polymer 5 was min, the adsorption capacity also examined at 100 mg L imprinted polymer has highernon-imprinted affinity for polymer. the This templatepolymer demonstrated than may the have that several imprinted the cavitiessites, and imprinted which specific were binding synthesised by the imprinting effect. results showed that the adsorption capacity oftoward imprinted olaquindox, polymer mequindox and quinocetone at 100 mg L were 7.86 mg g Figure 6. non-imprinted polymer increased withtial the concentration increasing of of olaquindox. theimprinted The ini- polymers adsorption was more capacity than of 1.5-fold thatpolymers the of at non-imprinted 100 mg L Figure 5. polymer. which demonstrated the MIP was abledifferences between to the recognise olaquindox and the its analogues. structural Results also showed that the mequindox has more closely related structure imprinted polymer, two compoundscharacteristics of with quinocetone and mequindox similar were selected, structurethe and imprinted polymer and toward the mixture of olaquindox, mequin- dox and quinocetone at 100 mg L was 68.32% of the saturated adsorptionwas almost capacity, reached and equilibrium adsorption within 3.0of h. olaquindox If the was concentration lower,shorter. the The time rapid adsorption to kinetics saturation ofan the would obvious imprinted advantage become polymer for is its applicationof in olaquindox SPE residues for in animal determination feeds or food products. 1 2 2 − 800, × www.soci.org Zhixiang Xu 2011 Society of Chemical Industry c vibration,which 2 had been grafted 2 indicated–NH 1 − 26,27 800. × Scanning electron micrographs of (a) activated silica gel, The binding affinity of the resulting MIP was evaluated by (b) (a) indicated that the functional monomer of APTES had the–NH wileyonlinelibrary.com/jsfa Characterisaction of adsorption ability The structure of the activated silica gel and newwas imprinted visualised polymer using SEM, as shownthat in Fig. the 4. It surface was clearly ofand evident the bald activated silica (Fig. 4a).that sphere many was However, particles very the attached smooth (Fig. imprinted 4b). on the polymer These activated exhibited results silica suggested gel that–NH surface and (b) imprinted polymer, group of APTES, whichhad indicated reacted that with functional the monomerpolymer template had APTES been olaquindox and prepared. the imprinted group. The FTIR spectra of thethe imprinted polymer imprinted (c) showed polymer that alsoC–N had stretch, Si–O andresulted stretch, N–H from Si–O–Si stretch. the–NH The stretch, interaction features stretch, between around the–OH that 3448 could group cm of be olaquindox attributed and the–NH to the around3422,3240and3051 cm Figure 4. onto the surface of activatedAPTES had silica been gel combined after with modification, thesilica surface gel so of sorbent the the and functionalised itolaquindox might during have the reacted polymerised process. with the template of equilibrium adsorption experiment, andnon-imprinted polymer was 20 incubated mg with 10 mL of of differentcentrations con- imprinted of or olaquindox in acetonitrile solution.data The (Fig. adsorption 5) showed that the binding capacity of imprinted or

2382 2383 olaquindox at for 50 min. The , indicating that 1 1 1 − − − gL µ wileyonlinelibrary.com/jsfa . Results indicated that the 1 . Result indicated the non- 1 − − cartridges or MISPE-HPLC respectively 18 olaquindoxwasloadedbytheMIP cartridges, tration by (a) imprinted polymer sorbent, (b) non- 1 − gL flow rate and 50 min of sample loading time were µ 1 − . 1 − The optimisation of sample loading flow rate and time on the For selection of the optimum eluent volume applied in the Different sample acidities were investigated in the pH ranges MISPE were studied. It was foundof that olaquindox the chromatographic had peak noflow obvious rate variation decreased as from the 10.0 sample to loading 1.1 mL min eluting step, different volumes(95 : (0.1–1.5 5, v/v) were mL) tested. With of the elutingfrom solvent methanol/water 0.1 volume increasing to 0.3 mL, theincreased rapidly, chromatographic and peak then of decreased olaquindox inTherefore, was the 0.3 range mL of 0.3–1.5 of methanol/water mL. eluting (95 solution : in 5, the v/v) study. was used as the observed in the chromatograms.peak of olaquindox The was appeared biggest when eluted by chromatographic methanol/water (95 : 5, v/v) and then it reducedgreater. as the content Thus, of methanol became methanol/watereluting (95 solvent, : and 5, the loaded v/v) olaquindox can was be fully selected desorbed. as the at the flow rate of 2.0 mL min results showed that theolaquindox was biggest obtained chromatographic in the peak pHoptimum area pH range range of of resulted 7.0–8.0. in low Outside retentionMIP the of column, olaquindox on the the chromatographicpH peak value area of 7.7 decreased. was chosen Thus, for a the following step. Applicability and merits of MISPE-HPLC Figure 8 showscontaining 50 the 100 mL of standard acetonitrile solution NIP cartridges and C imprinted cartridge had little concentration effect(Fig. for 8b), olaquindox in comparisonwas to obviously appeared chromatogramfrom in (b), the the the imprinted chromatogram olaquindox cartridge,was (a) after which selectively eluting indicated extracted thatselectivity onto of olaquindox the the imprinted sorbent imprinted for olaquindox sorbent was very and high. the a sample flow rate of 2.0 mL min chromatographic peak areassample loading increased time increased almost up2.0 to linearly mL at min least as 50 min. the Therefore, a the kinetics forvery the fast. The adsorption influence of of sampleof loading olaquindox time olaquindox by on the was the adsorption investigated MIP was with 50 of 4.0–12.0 at a sample flow rate of 2.0 mL min chosen as the experimental conditions for further studies. , 1 − 2011 Society of Chemical Industry c standard solution. 1 − olaquindoxs standard solution after SPE preconcen 1 − gL µ sorbent, for 100 mL at a flow rate of 2.0 mL min 18 : 2378–2385 91 ABC 2011; HPLC chromatograms of the 50 Adsorption capacity of imprinted polymer toward olaquindox,

9 8 7 6 5 4 3 2 1 0

Q (mg g (mg Q ) -1 The composition of eluting solvent plays a vital role on the This might result from the imprinting effect, the difference of Determination of olaquindox in chick feeds www.soci.org 40% olaquindox was selectivelyThe imprinted adsorbed sorbent on cartridge theof was MIP firstly methanol/water sorbent. washed (40 withdifferent : 60, 0.5 proportion mL of v/v), methanol/waterResults to then showed desorb that the eluted the template. absorbedmethanol/water olaquindox with at was not proportion 0.5 eluted mL of by 80 : of 20 (v/v) and no signal was imprinted polymer sorbent, and (c) C J Sci Food Agric Figure 8. MISPE procedure. Afterpassed 100 through mL MISPE cartridge standard at olaquindox a flow solution rate of 2.0 mL min Optimisation of the MISPE procedure With good characters,determinationoftraceolaquindoxbyon-lineSPE-HPLC.Toachieve the MIP wasgood applied sensitivity as and sorbent precisionthe for adsorbed for olaquindox, the the the MISPE conditions extraction such asand composite and volumes elution of of elutionflow solution, rate sample and acidity, time, were sample optimised. loading A; mequindox, B; and quinocetone, C; at 100 mg L to olaquindox (Fig. 1), and thehigher novel adsorption imprinted toward polymer mequindox exhibited than quinocetone. the molecular interactions and structures. Duringof the the preparation imprinted polymer, theporated template into of inorganic–organic olaquindox networks. was Subsequent removal incor- the of template molecule resulted in imprinted cavities whosesize shape, and spatial arrangement areand complementary specific to binding olaquindox, sitesorientation. of amino groups in a predetermined Figure 7. . Food et al :L347 3 :35–44 :49–61 :97–102 54 141 569 :7–14(2004). : 2378–2385 91 504 Acta Hydrobiol Sin :83–87 (2008). 2011; :110–117 (2009). :565–569 (2002). 6 1209 58 Off J Eur Commun :141–148 (1996). :105–119 (1986). Anal Chim Acta :128–134 (2009). :227–252 (2001). React Funct Polym Stud Surf Sci Catal 331 atalytically active, molecularly ve quinoxaline-1,4-dioxides in AnalChimActa 456 637 :468–475 (1998). growth promoters in animal feed. 906 pray, tandem mass spectrometry. 16 J Sci Food Agric J Chromatogr A J Mol Catal B: Enzym ¨ om J, Henschel H, Whitcombe MJ, Wikman S Anal Chim Acta :15–20 (2005). :99–109 (2003). J Chromatogr A Acta Veterin Zootech Sin Anal Chim Acta J Chromatogr A 816 483 ` Trends Biotechnol an-Vallvey LF, Fernandez MD, De Orbe I and Avidad R, :36–41 (2006). 44 ˙ e G, Naujalis E and Padarauskas A, Matrix solid-phase ` an F, Capit ¯ unait :23–26 (2003). dispersion extractionfollowed of bychromatographic carbadox hydrophilic analysis. and interaction ultra-high-pressure olaquindox liquid in feed poisoning in carp. carps by subacute toxicity test of olaquindox. 1 (1998). tion of residues of carbadoxtissues and by some of high itsline metabolites performance pre-column in enrichment liquid swine andUV–VIS post-column chromatography detection. derivatization using with on- ofmolecularly imprintedpolymers. (2003). Subchronic oral toxicityChem study Tox with cyadox in Wistar rats. carbadox andliquid olaquindox chromatography–electros metabolitesJ Chromatogr in B porcine liver using (2006). (2002). imprinted polymers in bead form. Determination ofspectrophotometry. colorant matters in foods by solid phase chromatography. of natural antibodies and enzymes. method for residues of the metabolites of carbadoxin and porcine olaquindox tissues. applications. and Nicholls IA,Diels–Alder Molecularly reaction. imprinted polymer catalysis of a animal feedsperformance liquid using chromatography. ultrasonic solvent extraction and high teghema CV, Liquid chromatographic–tandem mass spectrometric detection of banned antibacterial Anal Chim Acta Simultaneous determination of fi ¨ orje S, Imprinted chiral stationary phases in high performance liquid 1Kesi 2 Wang K and Geng Y, Pathological study on the acute olaquindox 3 Wang K and Geng Y, Studies on haematological changes in common 6 Aerts MML, Beek WMJ, Keukens HJ and Brinkman UATh. Determina- 4 Fang GJ, He QH, Zhou SQ,5 Wang Commission DJ, Regulation (EC) Zhang No.2788/98. YL and Yuan ZH, 7 Hutchinsona MJ, Youngb PB and Kennedyb DG, Confirmation of 8 Boison JO, Lee SC and Gedir RG, A determinative and confirmatory 9 Poucke CV, Keyser KD, Baltusnikiene A, McEvoy JDG and Pe- 12 Matthew PD, Vern DB and David P, Approaches13 to the rational B design 11 Capit 17 Strikovsky A, Hradil J and Wulff G, C 16 Wulff G, Molecular imprinting – a way to prepare effective mimics 14 Karsten H and15 Klaus M, Kirsch N, Plastic Hedin-Dahlstr antibodies: developments and 10 Wu YJ, Wang YL, Huang LL, Tao YF, Yuan ZH and Chen DM, a good selectivity, improved stability and high adsorptionfor capacity olaquindox. A sensitive and simpledetermination method of of MISPE-HPLC for trace olaquindoxThis method was was successfully applied for developed. dox enrichment in and animal analysis feed of samples olaquin- withFrom good this accuracy point and of repeatability. view, thismethod study for will the provide monitoring a of sensitive olaquindox and residues fast in foods. ACKNOWLEDGEMENTS The authorsChina are Postdoctoral Science grateful(project Foundation No. funded for project,& 20090451342), financial China and Technology the support2008GG10009026). of Department from Shandong of the Science Province, China (projectREFERENCES No. 3) 1 − = RSD, levels N 1 ± / www.soci.org Zhixiang Xu − S 0 0 cartridges . . 100 mL 5 2 2011 Society of Chemical Industry 18 ± ± SPE was com- c 0 0 . . 18 for loading 100 mL, an 1 − ) Recovery of olaquindox (%) 1 , and the RSD for five replicate − 1 − olaquindox was 9.8%. 1 3) 68.0 ng L − = ∗ gL N / µ S olaquindox standard solution. Recoveries of olaquindox in chicken samples (mean Accuracy and reproducibility of the MISPE-HPLC method 1 5) 9.8% − = extraction column (Fig. 8a). These results clearly indicated gL n 3) µ 18 = 50 The selectivity and enrichment of MISPE and C Furthermore, this MISPE column is stable and can be used The analytical figures of merits for the present of MISPE-HPLC Chick feed 0.010 96 Chick feed 0.0025 90 Table 2. ∗ RSD ( Actual sample Spiked level (mg g Enrichment factorDetection limit ( Enrichment volume n 80 Table 1. Parameter Value Accuracy of the MISPE-HPLC method The application and accuracy of MISPE-HPLC for pre-concentration and determination ofinvestigated. olaquindox The chickens in determined animalwere to spiked be food with free sample olaquindox of at olaquindox was 0.0025 and 0.010 mg g paredatthesamecondition.ResultsshowedthattheC extractions of 50 enrichment factor of MISPE was 80. The detection limit ( and were analysed, asconcentration, three shown measurements in were Tablerecoveries 2. performed, were and For achieved good each rangingthat sample from there was and 90% little to matrix effectsample 96%, in indicating the using analysis of the environmental sample treatment procedure. developed MISPE-HPLC without anyfor other more thansensitivity. 60 Thus, cycles the cost of perwas analysis the drastically of reduced. the procedure With MISPE-HPLC good method without selectivitythe and the practical MISPE-HPLC value, loss provided of determination of a trace olaquindox simple residues in and food samples. sensitive method for wileyonlinelibrary.com/jsfa CONCLUSIONS In this study, asized new by olaquindox-imprinted a polymer was surfacesol–gel synthe- molecular process technique. imprinting The imprinted in material exhibited combination with with a that this imprinted polymer wasfor more scientific suitable separation and as extraction an of SPE olaquindoxanalysis. prior sorbent to food method for determination ofoptimal olaquindox experimental conditions. were The data evaluated in Table under with 1 the indicate loading that flow rate of 2.0 mL min had concentration effect but no selectivitychromatogram (b) for was lower olaquindox, (Fig. so 8b). The the imprinteda cartridge had better selectivity and higherthe concentration C on olaquindox than based on three times the signal-to-noise ratiothe of analyte the baseline peak near was 68.0 ng L

2384 2385 J Agric Food wileyonlinelibrary.com/jsfa ly imprinted silica gel sorbent ormance liquid chromatography :131–136 (2005). , Molecular imprinting science and technology: :106–180 (2006). 1100 :1734–1439 (2005). 19 et al 77 :3869–3876 (2007). 55 sorbent prepared by a surface imprinting techniqueasol–gelprocessforselectivesolid-phaseextractionofcadmium(II). combined with Anal Chem characterization offor a the molecular on-linethrough determination high-performance of liquid traceChem chromatography. Sudan I in chilli powder molecularly imprinted sol–gelextraction couple material with high forfor the perf determination of on-line trace pentachlorophenol in solid-phase waterJ samples. Chromatogr A Nicholls IA, A survey of theMol literature Recognit for the years up to and including 2003. 26 Fang GZ, Tan J and Yan XP, An ion-imprinted functionalized silica gel 27 Wang S, Xu ZX, Fang GZ, Duan ZJ and Zhang Y, Synthesis and 25 Han DM, Fang GZ and Yan XP, Preparation and evaluation of a 24 Alexander C, Andersson HS, Andersson LI, Ansell RJ, Kirsch N, 2011 Society of Chemical Industry c J Agric Food Chem ¨ uggemann O, Food :1804–1808 (2002). 50 :163–173 (2000). mers to solid-phase extraction 739 ymers for the determination of :349–353 (2005). :274–279 (2010). 93 :325–328 (2006). 659 1132 J Agric Food Chem J Chromatogr B Food Chem , Catalytic molecularly imprinted polymer : 2378–2385 91 et al Anal Chim Acta 2011; J Chromatogr A ¨ om O, Skudar K, Haines J, Patel P and Br :2015–2114 (2001). Piletsky SA, membranes: Development of thedetection. biomimetic sensor for phenols the application ofand imprinted binding assay. poly Molecularly imprinted solid phase extraction for detection ofI Sudan in food matrices. for the selective solid-phasehoney. extraction of chloramphenicol from using molecularly imprinted pol quercetin in red wine. analyses using molecularly imprinted polymers. 14 18 Sergeyeva TA, Slinchenko OA, Gorbach LA, Matyushov VF, Brovko OO, 19 Andersson LI, Molecular imprinting for drug bioanalysis: A review on 20 Francesco P, Carmelo G, Francesca I, Rita M, Umile GS and Nevio P, 21 Christina S and Hans M, Synthesis of a molecularly imprinted polymer 22 Molinelli A, Weiss R and Mizaikoff B, Advanced solid phase extraction 23 Ramstr Determination of olaquindox in chick feeds www.soci.org J Sci Food Agric