Synthesis and application of imprinted polyvinylimidazole-silica hybrid copolymer for Pb determination by flow-injection thermospray flame furnace atomic absorption spectrometry

A novel ion imprinted polyvinylimidazole-silica hybrid copolymer (IIHC) was synthesized and used as a selective solid sorbent for Pb²⁺ ions preconcentration using an on-line solid phase extraction (SPE) system coupled to TS-FF-AAS. The ionic hybrid sorbent was prepared using 1-vinylimidazole and 3-(trimethoxysilyl)propylmethacrylate as monomers, Pb²⁺ ions as template, tetraethoxysilane as reticulating agent and 2,2′-azobis-isobutyronitrile as initiator. The best on-line SPE conditions concerning sorption behavior, including sample pH (6.46), buffer concentration (9.0 mmol L⁻¹), eluent (HNO₃) concentration (0.5 mol L⁻¹) and preconcentration flow rate (4.0 mL min⁻¹), were optimized by means of full factorial design and Doehlert matrix. The analytical curve ranged from 2.5 to 65.0 μg L⁻¹ (r = 0.999) with limit of detection of 0.75 μg L⁻¹; the precision (repeatability) calculated as relative standard deviation (n = 10) was 5.0 and 3.6% for Pb²⁺ concentration of 10.0 and 60.0 μg L⁻¹, respectively. From on-line breakthrough curve, column capacity was 3.5 mg g⁻¹. Preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 128.0, 0.16 mL and 25.6 min⁻¹, respectively. The selective performance of the sorbent, based on relative selectivity coefficient, was compared to NIC (non imprinted copolymer) for the binary mixture Pb²⁺/Cd²⁺, Pb²⁺/Cu²⁺ and Pb²⁺/Zn²⁺. The results showed that ion imprinted polyvinylimidazole-silica hybrid polymer had higher selectivity for Pb²⁺ than NIC at 64.9, 16.0 and 8.8 folds. The developed method was successfully applied for highly sensitive and selective Pb²⁺ determination in different kinds of water samples, parenteral solutions and urine. Accuracy was also assessed by analyzing certified reference fish protein (DORM-3) and marine sediment (MESS-3 and PACS-2) with satisfactory results.     

Preparation and evaluation of molecularly imprinted ionic liquids polymer as sorbent for on-line solid-phase extraction of chlorsulfuron in environmental water samples

In this report, vinylimidazolium ionic liquid as a functional monomer for preparation of chlorsulfuron (CS) imprinted polymers were first studied. The imprinted materials showed high selectivity for CS, and fast kinetics so that adsorption equilibrium was achieved within 5 min. These materials have been further employed to detect trace CS from water samples by online preconcentration coupled with HPLC. The sorbent offered good linearity (0.005-30 μg L(-1), r(2)>0.99) for on-line solid-phase extraction of trace chlorsulfuron. Under the optimal experimental conditions, the recovery for chlorsulfuron was in the range of 81.0-110.1% for the water samples, with RSDs ranging from 1.2 to 7.6%.     

Determination of crystal violet in seawater and seafood samples through off‐line molecularly imprinted SPE followed by HPLC with diode‐array detection

A highly selective sample cleanup procedure combined with molecularly imprinted SPE was developed for the isolation of crystal violet from seawater and seafood samples. The molecularly imprinted polymer was prepared using crystal violet as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. The crystal violet‐imprinted polymer was used as the selective sorbent for the SPE of crystal violet. An off‐line molecularly imprinted SPE method followed by HPLC with diode‐array detection for the analysis of crystal violet was also established. Good linearity on the molecularly imprinted SPE columns was obtained from 0 to 200 μg/L (R² > 0.99). The result demonstrated that the proposed method can be used for the direct determination of crystal violet in seawater and seafood samples. Finally, five samples were analyzed and the following crystal violet concentrations were obtained: 0.92 and 0.52 μg/L in two seawater samples, as well as 0.36 and 0.27 μg/kg in two seafood samples. There is no crystal violet detected in the third seawater sample.     

Inorganic-organic Ag-rhodamine 6G hybrid nanorods: "turn on" fluorescent sensors for highly selective detection of Pb2+ ions in aqueous solution

Lead metal ions are of great concern and the monitoring of their concentration in the environment has become extremely important. In the present study, a new inorganic-organic hybrid assay of Ag nanorods (AgNR)-Rhodamine 6G (R6G) was developed for the sensitive and selective determination of Pb(2+) ions in aqueous solutions. To the best of our knowledge there is almost no literature on the use of silver nanorod sensors for determination of lead ions in aqueous solutions. The sensor is developed by the coating of R6G on the surface of AgNRs. The sensing is based on the photoluminescence of R6G. The sensor was rapid as the measurements were carried out within 3 min of addition of the test solution to the AgNR-R6G hybrid. Moreover, the system showed excellent stability at tested concentration levels of Pb(2+) ions. The naked eye detection of the colour was possible with 1 mg L(-1) of Pb(2+) ions. The present method has a detection limit of 50 μg L(-1) of Pb(2+) (for a signal/noise (S/N) ratio > 3). The selectivity toward Pb(2+) ions against other metal ions was improved using chelating agents. The proposed method was validated by analysis using different techniques.     

Molecularly imprinted polymer grafted to porous polyethylene frits: a new selective solid-phase extraction format

In this paper, a novel format for selective solid-phase extraction based on a molecularly imprinted polymer (MIP) is described. A small amount of MIP has been synthesized within the pores of commercial polyethylene (PE) frits and attached to its surface using benzophenone (BP), a photo-initiator capable to start the polymerisation from the surface of the support material. Key properties affecting the obtainment of a proper polymeric layer, such as polymerisation time and kind of cross-linker were optimised. The developed imprinted material has been applied as a selective sorbent for cleaning extracts of thiabendazole (TBZ), as model compound, from citrus samples. The use of different solvents for loading the analyte in the imprinted frits was investigated, as well as the binding capacity of the imprinted polymer. Imprinted frits showed good selectivity when loads were performed using toluene and a linear relationship was obtained for the target analyte up to 1000 ng of loaded analyte. Prepared composite material was applied to the SPE of TBZ in real samples extracts, showing an impressive clean-up ability. Calibrations showed good linearity in the concentration range of 0.05-5.00 μg g(-1), referred to the original solid sample, and the regression coefficients obtained were greater than 0.996. The calculated detection limit was 0.016 μg g(-1), low enough to satisfactory analysis of TBZ in real samples. RSDs at different spiking levels ranged below 15% in all the cases and imprinted frits were reusable without loss in their performance.     

Solid-phase extraction using molecularly imprinted polymer for selective extraction of natural and synthetic estrogens from aqueous samples

A method is proposed for the clean-up and preconcentration of natural and synthetic estrogens from aqueous samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). The selectivity of the MIP was checked toward several selected natural and synthetic estrogens such as estrone (E1), 17β-estradiol (β-E2), 17α-estradiol (α-E2), estriol (E3), 17α-ethinylestradiol (EE2), dienestrol (DIES) and diethylstilbestrol (DES). Ultrahigh pressure liquid chromatography (UHPLC) coupled to a TSQ triple quadrupole mass spectrometry (QqQ) was used for analysis of target analytes. The chromatographic separation of the selected compounds was performed in less than 2 min under isocratic conditions. The method was applied to the analysis of estrogens in spiked river and tap water samples. High recoveries (>82%) for estrone, 17β-estradiol, 17α-estradiol, estriol and 17α-ethinylestradiol were obtained. Lower but still satisfactory recoveries (>48%) were achieved for dienestrol and diethylstilbestrol. The method was validated and found to be linear in the range 50-500 ng L(-1) with correlation coefficients (R(2)) greater than 0.995 and repeatability relative standard deviation (RSD) below 8% in all cases. For analysis of 100-mL sample, the method detection limits (LOD) ranged from 4.5 to 9.8 ng L(-1) and the limit of quantitation (LOQ) from 14.9 to 32.6 ng L(-1). To demonstrate the potential of the MIP obtained, a comparison with commercially available C(18) SPE was performed. Molecularly imprinted SPE showed higher recoveries than commercially available C(18) SPE for most of the compounds. These results showed the suitability of the MIP-SPE method for the selective extraction of a class of structurally related compounds such as natural and synthetic estrogens.     

Determination of five priority haloacetic acids by capillary electrophoresis with contactless conductivity detection and solid phase extraction preconcentration

A sensitive capillary electrophoretic separation method with contactless conductivity detection (C4D) for analysis of five priority haloacetic acids (HAA5) is presented. The analytes were baseline separated in an electrolyte composed of 20 mM 2-(N-Morpholino) ethanesulfonic acid (MES), 20 mM L-histidine (HIS), and 30 μM cetyltrimethylammonium bromide (CTAB) at pH 6.0 in less than 4 min. A simplified solid-phase extraction (SPE) preconcentration procedure on highly cross-linked polystyrene-divinylbenzene (PS-DVB) type sorbent was developed and optimized with respect to short preconcentration time. HAA5 from a 25-mL sample aliquot of tap and swimming pool water could be preconcentrated in less than 5 min using an in-house made SPE column with recoveries ranging from 23 to 98%. Combining the SPE preconcentration procedure with capillary electrophoretic analysis, the attained limits of detection were between 6.1 and 12.2 μg/L with total analysis time of less than 10 min.     

Development of andrographolide molecularly imprinted polymer for solid-phase extraction

A method employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE) to pretreat samples was developed. The polymers were prepared by precipitation polymerization with andrographolide as template molecule. The structure of MIP was characterized and its static adsorption capacity was measured by the Scatchard equation. In comparison with C(18)-SPE and non-imprinted polymer (NIP) SPE column, MIP-SPE column displays high selectivity and good affinity for andrographolide and dehydroandrographolide for extract of herb Andrographis paniculata (Burm.f.) Nees (APN). MIP-SPE column capacity was 11.9±0.6 μmol/g and 12.1±0.5 μmol/g for andrographolide and dehydroandrographolide, respectively and was 2-3 times higher than that of other two columns. The precision and accuracy of the method developed were satisfactory with recoveries between 96.4% and 103.8% (RSD 3.1-4.3%, n=5) and 96.0% and 104.2% (RSD 2.9-3.7%, n=5) for andrographolide and dehydroandrographolide, respectively. Various real samples were employed to confirm the feasibility of method. This developed method demonstrates the potential of molecularly imprinted solid phase extraction for rapid, selective, and effective sample pretreatment.     

Reversed phase StrataTM-X resin as sorbent for automatic on-line solid phase extraction atomic absorption spectrometric determination of trace metals: comparison of polymeric-based sorbent materials

A novel on-line flow injection solid phase extraction method for the preconcentration of trace toxic metals prior determination by flame atomic absorption spectrometry (FI-SPE-FAAS) was developed. The potential application of the hydrophobic reversed phase co-polymer sorbent Strata^TM-X packed into an on-line microcolumn for the quantification of Cd(II), Pb(II), Cu(II) and Cr(VI) was demonstrated for the first time. The method was based on the on-line formation of metal complexes using sodium diethyl-dithiocarbamate (DDTC) and on the subsequent retention of them onto the sorbent material. The target analytes were completely eluted by methanol and, subsequently, directed to FAAS for quantification. All chemical and flow variables affecting the performance of the developed method were thoroughly studied and optimised. For a preconcentration time of 90 s and a sampling frequency of 28 h^?1, enhancement factors of 72, 140, 185, 63 and detection limits of 0.18, 1.6, 0.20 and 1.2 μg L ^?1 were obtained for Cd(II), Pb(II), Cu(II) and Cr(VI), respectively. The accuracy of the FI-SPE-FAAS method was evaluated by analysing certified reference materials as well as spiked environmental water samples. Furthermore, a comparative study of the analytical characteristics, the properties as well as the chemical structures of commercial polymeric based sorbent materials was employed. Strata-X sorbent was compared against Hypersep^TM SCX, Bond Elut® Plexa^TM PCX, Oasis-HLB^TM and Nobias^TM PA-1, regarding the adaptation in on-line FI-SPE-FAAS systems for metal determination, and herein presented.     

A comprehensive chromatographic comparison of amphetamine and methylamphetamine extracted from river water using molecular imprinted polymers and without the need for sample derivatization

This work explores the differences between two GCMS instruments for the determination of amphetamine and methylamphetamine extracted from water samples (ultra pure water and river water) without the necessity for derivatization. The instruments contained different generations of gas chromatograph and mass selective detector components and revealed significantly different results when presented with the same samples. The extraction methodology also compared two SPE systems. The extraction efficiency of commercially available molecular imprinted polymers as a sorbent in SPE was compared with commonly used hydrophilic balance sorbent. Molecular imprinted polymers provided excellent recoveries (81 ± 2% and 108 ± 3% at 30 μg L^?1, and 94 ± 2% and 94 ± 2% at 200 μg L^?1 for amphetamine and methylamphetamine, respectively). The best LOD obtained was sufficient for the determination of both drugs extracted from river water (0.029 ± 0.003 and 0.015 ± 0.004 μg L^?1 for amphetamine and methylamphetamine, respectively). These were comparable to literature values obtained through conventional extraction and analysis using LC‐MS/MS but had the advantage of being achieved using an underivatized GCMS method.     

Application of molecularly imprinted polymer for solid phase extraction and preconcentration of Hydrochlorothiazide in pharmaceutical and serum sample analysis

A new polymeric sorbent prepared by utilizing molecular imprinting technology was used for the selective extraction of hydrochlorothiazide (HCT) from pharmaceutical and human serum sample. The molecularly imprinted polymer (MIP) was prepared using HCT as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EDMA) as the cross-linker monomer, and dimethylformamide (DMF) as a solvent. The optimized conditions of MIPs as a selective sorbent for the preconcentration of the HCT were studied. The results showed that the drug could be quantitatively and selectively maintained in the column to be then eluted from the sorbent by using methanol-acetic acid mixture (9:1). HCT could be determined spectrophotometrically at λ_max = 270 nm. This method made it possible to quantitize HCT in the range of 0.1–21.0 μg ml^-1, by less than 0.55% of RSD%, with a detection limit (S/N = 3) of 0.073 ng ml^-1. The preconcentration factor of 1000, recoveries of up to 96% and retention capacity of 75.0 mg g_-1 were achieved using this technique.     

On-line selective solid-phase extraction of 4-nitrophenol with β-cyclodextrin bonded silica

The selective analysis of 4-nitrophenol (4-NP) from water samples using on-line solid-phase extraction (SPE) coupled to HPLC system was studied. The β-cyclodextrin bonded silica (CDS) was utilized as the selective sorbent. Using 100 ml of sample solution spiked with 4-nitrophenol and other six phenols (Ph) in double distilled water, the sorbent showed strong capacity in adsorbing 4-nitrophenol and the recovery was 104% with the detection limit of 0.017 μg/l. The selectivity was investigated by utilizing a washing step with acetonitrile after preconcentration and only 4-nitrophenol was detected with the recovery of 99%. Donghu lake (Wuhan, China) water sample was used to test the on-line SPE-HPLC system and 4-nitrophenol was selectively extracted with the recovery obtained as 90%.     

Solid-phase extraction of polar compounds with a hydrophilic copolymeric sorbent

A new synthesized copolymer based on N-vinylimidazole-divinylbenzene (VIm-DVB) was tested as a sorbent for the solid-phase extraction (SPE) of polar analytes. In the on-line SPE, this synthesized sorbent enabled 100 ml of sample to be preconcentrated with recoveries as high as 80% for oxamyl, phenol (Ph) and derivates, bentazone and (4-chloro-2-methylphenoxy)acetic acid (MCPA). For the off-line SPE, 1000 ml of sample was extracted and recoveries were higher than 92% for all compounds with the exception of oxamyl (83%) and methomyl (78%). The VIm-DVB sorbent gives better recoveries than the previously synthesized 4-vinylpyridine-divinylbenzene (VP-DVB) resin and similar to such highly crosslinked commercial sorbents as LiChrolut EN or Oasis HLB. Real water samples were used to validate the on-line SPE method. Linearity was good and detection limits were between 0.1 and 0.2 microg l(-1).     

Tandem use of solid-phase extraction and dispersive liquid-liquid microextraction for the determination of mononitrotoluenes in aquatic environment

Solid‐phase extraction (SPE) in tandem with dispersive liquid–liquid microextraction (DLLME) has been developed for the determination of mononitrotoluenes (MNTs) in several aquatic samples using gas chromatography‐flame ionization (GC‐FID) detection system. In the hyphenated SPE‐DLLME, initially MNTs were extracted from a large volume of aqueous samples (100 mL) into a 500‐mg octadecyl silane (C₁₈) sorbent. After the elution of analytes from the sorbent with acetonitrile, the obtained solution was put under the DLLME procedure, so that the extra preconcentration factors could be achieved. The parameters influencing the extraction efficiency such as breakthrough volume, type and volume of the elution solvent (disperser solvent) and extracting solvent, as well as the salt addition, were studied and optimized. The calibration curves were linear in the range of 0.5–500 μg/L and the limit of detection for all analytes was found to be 0.2 μg/L. The relative standard deviations (for 0.75 μg/L of MNTs) without internal standard varied from 2.0 to 6.4% (n=5). The relative recoveries of the well, river and sea water samples, spiked at the concentration level of 0.75 μg/L of the analytes, were in the range of 85–118%.     

Molecularly imprinted on-line solid-phase extraction combined with flow-injection chemiluminescence for the determination of tetracycline

A molecularly imprinted polymer solid phase extraction (MISPE) method combined with flow-injection chemiluminescence (FI-CL) for the determination of residual tetracycline (TC) in fish samples is presented. The molecularly imprinted polymer (MIP) of TC was synthesized and particles of this MIP were packed into a polytetrafluoroethylene (PTFE) tube, which was connected into the sampling loop of an eight-way injection valve and served as the MISPE column for on-line selective adsorption of TC. The eluent (CH3CN : HNO3 (0.01 mol L(-1)) = 4 ratio 1, v ratio v) was used for extracting the adsorbed TC, which could be detected by its good enhancing effect on the CL reaction between Ce(iv) and rhodamine B. The CL intensity is linear to TC concentration in the range from 4 x 10(-9) to 4 x 10(-7) g mL(-1). The detection limit is 1 x 10(-9) g mL(-1) (3 sigma) and the relative standard deviation is 2.4% (n = 9). The conditions of preconcentration, extraction and CL reaction were carefully studied. The selectivity experiment shows that the selectivity and sensitivity of the CL method could be improved greatly when MIP was used as a recognition material in SPE. However, the MISPE column interacted indiscriminately with oxytetracycline (OTC) with a 49 +/- 2% binding. An intermediate differential pulsed elution (DPE) step using 3% acetic acid as eluent was employed to remove OTC and other interfering substances. The proposed MISPE-CL method has been applied successfully to the determination of TC in fish samples. At the same time, the binding characteristics of the polymer to tetracycline were evaluated by batch and dynamic methods.     

Determination of 1-hydroxypyrene in human urine by HPLC with electrochemical detection at a boron-doped diamond film electrode

A high-performance liquid chromatographic method with electrochemical detection (HPLC-ED) at a boron-doped diamond film electrode with preliminary separation and preconcentration by solid-phase extraction (SPE) has been developed for the determination of 1-hydroxypyrene (1-HP) in human urine. 1-HP is among the most widely used biomarkers of exposure to polycyclic aromatic hydrocarbons. Optimal HPLC-ED conditions have been found: mobile phase methanol-0.05 mol L(-1) phosphate buffer pH 5.0 (80:20, v/v), detection potential +1,000 mV versus Ag/AgCl (3 mol L(-1) KCl), and flow rate 0.8 mL min(-1). For SPE, LiChrolut(?) RP-18 E cartridges were used. The extraction yield was (87.0 ± 5.8)% (n = 5). The concentration dependence of 1-HP was measured in the concentration range from 0.01 to 10 μmol L(-1) (2.18-2,180 μg L(-1)) using methanolic solutions resulting from the SPE pretreatment of spiked human urine samples. The limit of detection (signal-to-noise ratio 3) and the limit of quantification (signal-to-noise ratio 10) of the biomarker were 0.013 μmol L(-1) (2.84 μg L(-1)) and 0.043 μmol L(-1) (9.39 μg L(-1)), respectively, which is sufficient for its determination in the urine of persons exposed to polycyclic aromatic hydrocarbons.     

苏丹红I分子印迹聚合物的制备及其性能评价

以苏丹红I为模板分子,通过沉淀聚合法制备了一种对苏丹红I具有特异性吸附的分子印迹聚合物。通过选择性评价和前沿色谱实验,评价了致孔剂的选择和用量、功能单体和模板分子的物质的量比对分子印迹聚合物识别性能的影响。实验结果表明: 当以甲醇和乙腈的混合液(体积比为30:10)为致孔剂,甲基丙烯酸(MAA)为功能单体,且功能单体和模板分子的物质的量比为8:1时,分子印迹聚合物的印迹因子为2.32,亲和位点总数(Bt)为0.50 μmol/g;将其作为固相萃取柱填料用于辣椒粉样品中痕量苏丹红I的净化和富集,结果表明: 苏丹红I浓度在10～500 μmol/L范围内时,呈现良好的线性关系(r=0.999);检出限为3.3 μmol/L,加标回收率为95.87%～98.41%,相对标准偏差低于3.1%。该方法有望用于辣椒粉样品中苏丹红I添加剂的常规检测。     

Silica Gel-Immobilized 5-aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu,Zn and Pb from natural water samples

A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO₂-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO₂-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L⁻¹ for Cu, 7.4 μg L⁻¹ for Zn and 3.5 μg L⁻¹ for Pb μg L⁻¹. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO₂-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.     

Application of a magnetic molecularly imprinted polymer for the selective extraction and trace detection of lamotrigine in urine and plasma samples

Magnetic molecularly imprinted polymers have been synthesized for the selective preconcentration and trace determination of lamotrigine (LTG) in urine and plasma samples. The magnetic nanoparticles were modified by tetraethyl orthosilicate and 3‐methacryloxypropyl trimethoxysilane before imprinting. The magnetic molecularly imprinted polymers were prepared via surface molecular imprinting technique, using Fe₃O₄ as a magnetic component, LTG as template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross‐linker, and 2,2′‐azobisisobutyronitrile as a radical initiator in methanol/acetonitrile (50:50, v/v) as the porogen. The obtained sorbent was characterized using scanning electron microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, and thermal analysis. Separation of the sorbent from the sample solution was simply achieved by applying an external magnetic field. Determination of the extracted drug was performed by high‐performance liquid chromatography with UV detection. Under the optimum extraction conditions, the method detection limits were 0.7 μg/L (based on S/N of 3) for urine samples and 0.5 μg/L for plasma samples. A linear dynamic range of 1–1000 μg/L was obtained for LTF in plasma and urine samples. Finally, the applicability of the proposed method was evaluated by extraction and determination of LTG in urine and plasma samples.     

Preparation and application of a molecularly imprinted polymer for the determination of trace metolcarb in food matrices by high performance liquid chromatography

In this article, for the first time, a molecularly imprinted polymer (MIP) for the metolcarb was prepared by bulk polymerization using metolcarb as the template, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross‐linker. The prepared polymer was characterized by FT‐IR, static and kinetic adsorption experiments, and the results showed that it has been successfully synthesized and had good selective ability for metolcarb. The MIP was applied as a sorbent in molecularly imprinted SPE coupled with HPLC‐UV for separation and determination of trace metolcarb in three kinds of food matrices at three concentration levels. Under the optimal conditions, the LODs (S/N=3) of cabbage, cucumber and pear were 7.622, 6.455 and 13.52 μg/kg, respectively, and recoveries were in the range of 68.80–101.31% with RSD (n=3) below 3.78% in all cases. To demonstrate further the selectivity of the MIP obtained, a comparison with commercially available C₁₈ SPE was performed. The results indicated that molecularly imprinted SPE showed better chromatography, better selectivity and higher recoveries for metolcarb than commercially available C₁₈ SPE.