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Indole-3-carbinol (I3C), an important anticancer compound found in broccoli, has attracted considerable attention. The rapid extraction and accurate analysis of I3C in the pharmaceutical industry in broccoli is challenging as I3C is unstable at low pH and high temperature. In this study, a rapid, accurate, and low-cost ultrasound-assisted dispersive-filter extraction (UADFE) technique based on poly(deep eutectic solvent)-graphene oxide (PDES-GO) adsorbent was developed for the isolation and analysis of I3C in broccoli for the first time. PDES-GO with multiple adsorption interactions and a fast mass transfer rate was synthesized to accelerate adsorption and desorption. UADFE was developed by combining dispersive solid-phase extraction (DSPE) and filter solid-phase extraction (FSPE) to realize rapid extraction and separation. Based on the above two strategies, the proposed PDES-GO-UADFE method coupled with high-performance liquid chromatography (HPLC) allowed the rapid (15–16 min), accurate (84.3–96.4%), and low-cost (adsorbent: 3.00 mg) analysis of I3C in broccoli and was superior to solid-phase extraction, DSPE, and FSPE methods. The proposed method showed remarkable linearity (r=0.9998; region: 0.0840–48.0 μg/g), low limit of quantification (0.0840 μg/g), and high precision (relative standard deviation ≤ 5.6%). Therefore, the PDES-GO-UADFE-HPLC method shows significant potential in the field of pharmaceutical analysis for the separation and analysis of anti-cancer compounds in complex plant samples.

Molecularly imprinted polymers (MIPs) are conventionally synthesized in organic solvents, resulting in poor compatibility with water and weak molecular recognition of targets in aqueous environments; hence, developing a green process to synthesize such MIPs would make the procedure more sustainable and the production more environmentally scalable. To achieve these objectives, a new deep eutectic solvent-based hydrophilic molecularly imprinted resin (DES-HMIR) was synthesized in water with excellent selective molecular recognition in aqueous phase; thus, the process pre-empts the consumption of large amounts of organic solvents. During the synthesis, the DES was simultaneously used as a porogen and cosolvent for the template, in order to improve the imprinting factor and increase the specific surface area of the DES-HMIR. Owing to its specific recognition performance and water phase compatibility, the DES-HMIR can specifically recognize and extract targets from aqueous matrices. The obtained DES-HMIR showed excellent specificity towards analytes compared to commercial adsorbents such as HLB, C18, silica and SCX. The DES-HMIR could be easily regenerated with only 0.1 mL of 50% acetonitrile–water at room temperature and reused 26 times without a significant decrease in the adsorption capacity at pH 7. The DES-HMIR demonstrated excellent and specific recognition properties toward its target molecules in aqueous matrices, thereby allowing its use in a variety of promising applications, including environmental, biological, and clinical applications. Finally, the synthesis strategy proposed in this work provides a simple, efficient and green protocol for the preparation of water-compatible MIPs.

The overuse of swelling agents in fruits and vegetables has rapidly increased, resulting in food safety problems. Hence, a new method for the selective extraction and detection of thidiazuron (TDZ) and forchlorfenuron (KT30) was developed using deep eutectic solvent-molecularly imprinted hydrophilic resin (DES-MIHR) as a pipette tip solid-phase extraction (PT-SPE) adsorbent with excellent molecular recognition in aqueous matrixes. DES-MIHR interacted with TDZ and KT30 via π-π interactions and hydrogen bonding. The miniaturized PT-SPE can be performed with just 5.0 mg adsorbent, 0.3 mL water, and 0.2 mL eluent, thus having the advantage of the low consumption of adsorbent and organic reagents. The performance of the DES-MIHR-PT-SPE-high-performance liquid chromatography (HPLC) method was demonstrated with the recoveries from various fruits and vegetables being 81.1-102.9 % (RSD ≤ 7.1 %). Thereby indicating the general applicability of the developed method for the accurate determination of trace swelling agents in fruits and vegetables.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are emerging pollutants that threaten food safety. Herein, a rapid, accurate, and selective method for determination of PFOA and PFOS in milk was established by using new molecularly imprinted phenolic resin (MIP-PR) as the adsorbent of dispersive filter extraction (DFE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). MIP-PR was synthesized at room-temperature using m-aminophenol, glutaraldehyde, and perfluorononanoic acid as the monomers, cross-linkers, and virtual templates, respectively, and exhibited rapid mass transfer (30 s), high selectivity (imprinted factors 3.7), and large adsorption capacity (54.6 mg/g). Compared with reported methods, the developed MIP-PR-DFE method is fast, selective, inexpensive, and shows good purification and enrichment efficiency. The proposed MIP-PR-DFE-LC-MS/MS exhibited low limits of detection (0.006-0.022 ng/mL), high recoveries (94.7-109 %), and good precision (RSDs ≤ 9.5 %). This study provides a new idea for the development of imprinted resin adsorbents for perfluorinated compound, and a new method for sample pretreatment for monitoring of PFOA and PFOS in food.

The overuse of plant growth regulators (PGRs) in agricultural products has gradually increased in recent years, resulting in hazardous effects on food safety and human health. For the first time, a sensitive, accurate, and low-cost analytical method involving improved solid-phase extraction coupled with high-performance liquid chromatography was developed to determine trace PGRs in cherry tomatoes. Thereafter, the extraction mechanism and conditions were elucidated. Under optimized conditions, good linearity (0.04-400 ng g-1; r ≥ 0.9996) and lower limits of detection (0.005-0.006 ng g-1) were observed. The recoveries were 81.4-90.1%, with relative standard deviations of ≤6.7% (three levels). Finally, the developed method was successfully used to detect trace PGRs in cherry tomatoes. The results illustrated that this sensitive method shows great potential for application to monitor trace PGRs in agricultural products and, thus, provide technical support for food safety and public health.

The synthesis of biomacromolecule imprinted materials is a challenge with the bulkiness and instability of macromolecule, such as protein. A green strategy to prepare hydrophilic protein-imprinted resin (HPIR) was firstly developed using resorcinol and melamine as double functional monomers, hexamethylenetetramine instead of formaldehyde as crosslinker, water as solvent, and bovine serum albumin (BSA) as a dual-function template. BSA as dual-function template could not only act as template but also porogen in the preparation of HPIR. According to the adsorption experiments, the adsorption kinetics of BSA on HPIR obeyed pseudo-second-order adsorption kinetics and the equilibrium data were best described by Langmuir isotherm model. The adsorption capability was 44.3459 mg g−1 (25 °C), and the imprinted factor for binding BSA is 5.78. HPIR showed high adsorption capacity, fast mass transfer rate, and specific selectivity towards BSA in aqueous solvent. More importantly, HPIR can be applied to selectively adsorb target protein BSA in urine without the matrix interference of biological matrix, therefore, it is promising for HPIR to be applied to proteomics, diagnostics, and pharmaceutics.

The massive accumulation of plant growth regulators (PGRs) in Panax ginseng causes serious harm to human health. A new analytical method for the simultaneous determination of multiple PGRs in 19 types of fresh Panax ginseng is developed by a new designed wool cluster-inspired ionic liquid-functionalized ordered mesoporous silica-integrated dispersive solid-phase extraction coupled to high performance liquid chromatography (IL-WFOMS-I-DSPE-HPLC). The proposed method combines the advantages of the multiple adsorption mechanisms, high mass transfer rate and large adsorption capacity of the synthesized IL-WFOMS adsorbent with the safe, convenient operation of the new designed I-DSPE method. Under optimized conditions, the recoveries at three spike levels were in a range of 77.6–98.3% for 3-indole acetic acid (IAA), 3-indole propionic acid (IPA), 3-indole butyric acid (IBA), and 1-naphthaleneacetic acid (NAA) with the relative standard deviations (RSD) ≤8.6%, n = 3. This method exhibits the advantages of safety, convenience, reliability, and has great potential for simultaneous determination of multiple trace PGRs in complex sample matrices.

In this study, a novel and green synthesis of a new hydrophilic molecularly imprinted 3-aminophenol−hexamethylenetetramine (MIAPH) resin for the selective recognition and separation of plant hormones was developed. The MIAPH resin was obtained using 3-aminophenol as multifunctional monomer which introduced hydroxyl, amino, and imino groups simultaneously, and adenine was used as a dummy template for molecular imprinting. Meanwhile, hexamethylenetetramine released formaldehyde slowly through hydrolysis which was used as the cross-linking agent to avoid the direct and excessive use of toxic formaldehyde. The entire procedure was performed under mild conditions, and was facile, environmentally friendly and energy-efficient. The obtained MIAPH resin showed high specific recognition toward plant hormones and higher recoveries in bean sprouts compared to NIAPH, HLB, and C18. Various parameters affecting the extraction efficiency were optimized, and the calibration linearity of the MIAPH‒SPE‒HPLC method was determined from 0.07 to 2.86 mg kg−1 with a correlation coefficient (r) ≥ 0.9994 under the optimal conditions. Recoveries of spiked standards ranged from 90.2 to 99.1% for bean sprout with a relative standard deviation of ≤5.3%. Finally, the established MIAPH‒SPE‒HPLC method was successfully applied for the selective extraction and sensitive detection of plant hormones in a variety of complex vegetable matrices.

New hydrophilic molecularly imprinted melamine-urea-formaldehyde monolithic resin (MIMR) is synthesized using dopamine hydrochloride as a dummy template via in-situ polymerization directly within pipette tips and it presents special molecular recognition to plant growth regulators in aqueous matrices. Hydrophilic groups (such as hydroxyl groups, imino groups, and amino groups) can be introduced into MIMR by melamine- urea-formaldehyde resin, which make MIMR materials compatible with aqueous media and show their specific molecular recognition in aqueous sample solutions. Meanwhile, monolithic structures avoid the influence of uneven filling on the extraction efficiency. Various parameters affecting the selective recognition of MIMR have been optimized, such as molar ratio of melamine to urea, molar ratio of melamine and urea to formaldehyde, the amount of template and porogen. The prepared MIMR is applied as the sorbents of solid phase extraction (SPE) for sensitive and selective recognition of three plant growth regulators (p-chlorophenoxyacetic acid, 1-naphthaleneacetic acid and 2.4-dichlorophenoxyacetic acid) in bean sprouts. Considering its excellent hydrophilicity and specificity, MIMR-SPE is promising to be a potential pretreatment strategy in biological, environmental, and clinical fields.

A mimic molecularly imprinted ordered mesoporous silica (MIOMS) adsorbent was prepared utilizing a thermally reversible semicovalent approach. The thermally reversible covalent template-monomer complex was firstly synthesized by employing 4,4′-sulfonyldiphenol (BPS) and (3-isocyanatopropyl) triethoxysilane (ICPTES) as template and monomer, respectively. The template-monomer complex was incorporated into ordered mesoporous silica via a simple self-assembly process. The adsorption experiment illustrated that the imprint-removed silica (MIOMS-ir) had higher special recognition ability (250 μg g −1 ) for estradiol (E2) than the non-imprinted silica (NIOMS-ir) (25 μg g −1 ). MIOMS-ir was applied as an adsorbent in pipette-tip solid-phase extraction (PT-SPE) coupled with liquid chromatography-fluorescence detector (LC-FLD) for determination of E2 in milk samples. Under the optimized conditions, only 3 mg of the adsorbent, 0.3 mL of water as washing solvent, and 0.5 mL of acetonitrile-acetic acid (96:4, v/v) as elution solvent were used in the pretreatment procedure of milk samples. Good calibration linearity was obtained in a range of 25 ng L −1 to 1000 ng L −1 , and the recoveries at three spiked levels were ranged from 95.4% to 107.0% with relative standard deviations (RSDs) ≤3.1% (n = 3). The proposed MIOMS-ir-PT-SPE-LC-FLD method combined the advantages of PT-SPE and ordered mesoporous material such as ease assembly, low cost, high extraction efficiency and large specific surface area, so it is a potential pretreatment strategy for the extraction and determination of E2 in complex milk samples.

A new type of molecularly imprinted ionic liquid magnetic microspheres was synthesized by aqueous suspension polymerization, using 4,4'-dichlorobenzhydrol as a dummy template, and 1-allyl-3-ethylimidazolium hexafluorophosphate and methacrylic acid as co-functional monomers. The results of morphology and magnetic property evaluation of the obtained microspheres demonstrated that it was monodispersed spherical, possessed a rough surface, and an outstanding magnetic properties. Binding experiments revealed that it had a substantial adsorption capacity and strong recognition ability to organochlorine pesticides (OCPs) in aqueous solution. Then the microspheres were applied as an adsorbent of magnetic dispersive solid-phase extraction for the selective recognition and rapid determination of OCPs in environmental water. Under the optimum conditions, good linearity of the three types of OCPs (dicofol, tetradifon, and p,p'-dichlorodiphenyldichloroethane) was achieved in the range of 1.0-100 ng/mL (r ≥ 0.9994). The recoveries at three spiking levels ranged from 82.6 to 100.4% with the RSDs less than 6.9%.

A new ionic liquid functionalized graphene-pipette-tip solid-phase extraction method coupled with high-performance liquid chromatography was established for the simultaneous extraction and determination of three auxins in soybean sprouts. The graphene adsorbent, with multiple adsorption mechanisms, was first synthesized by functional modification of pentafluorobenzyl imidazolium bromide ionic liquid through thiol-ene click chemistry. The ionic liquid was applied to prevent the aggregation of graphene; it also imbued graphene with the ability for π-π interactions, ionic exchange, electrostatic interactions, as well as hydrogen bonding (which is stronger than the interaction between water and analytes), by augmenting the adsorption mechanisms between the adsorbent and analytes. Under optimized conditions, linearity was achieved in the ranges 0.03–5.00 µg/g for indole-3-acetic acid and 1-naphthaleneacetic acid and 0.09–5.00 µg/g for 2,4-dichlorophenoxyacetic acid, with a detection limit of 0.004–0.026 µg/g; this adsorbent has been successfully applied for the determination of auxins in soybean sprouts.

A new ionic liquid-magnetic graphene (IL-MG) composite was used as the adsorbent in magnetic dispersive solid-phase extraction to rapidly extract and isolate triazine herbicides from surface water. IL-MG was synthesized by a simple and time-saving one-pot strategy where the synthesis of magnetic Fe3O4, the modification with an IL, and the reduction of graphene oxide to graphene were conducted at the same time. An IL was applied to enrich the interaction mechanism between IL-MG and analytes (π–π, hydrophobic interaction, and electrostatic interaction). Moreover, the IL and Fe3O4 nanoparticles acted as spacers, inserting between the layers of graphene to prevent the aggregation of graphene, which improved the adsorption ability because of the large specific surface area of IL-MG. The resultant IL-MG had hierarchical flake structures and showed a high adsorption capacity (8266.0–12 324.1 μg g−1) toward triazine herbicides. Under suitable conditions, the linearity for triazine herbicides was achieved in the range of 0.55–500 ng mL−1 with a detection limit of 0.09–0.15 ng mL−1 and a quantitation limit of 0.31–0.51 ng mL−1, and the enrichment factor was 83-fold, which indicated that the proposed method could be successfully applied for the determination of triazine herbicides in surface water.

A C8-and-amino-bifunctionalized ordered mesoporous organosilica (C8-AMS) was prepared in a deep eutectic solvent—a green solvent—that was used as the reaction medium for this procedure instead of organic solvents or other catalyst for the first time. This method provided a nontoxic way for C8 grafting and obtaining an ordered mesoporous organosilica material with both hydrophilic and hydrophobic groups. Besides advantages such as its large surface area, regular and uniform pore size, and hydrothermal stability, the obtained bifunctionalized C8-AMS also have two main functional groups in the obtained structure, C8 and amino, which enriched the adsorption mechanism of the material and as a result improved the adsorption selectivity of C8-AMS. Its performance as an adsorbent was estimated in extracting trace triazine herbicides from watermelon using solid-phase extraction (SPE) followed by high-performance liquid chromatography (HPLC). The proposed method provided satisfactory features in terms of linearity (0.01–2.00 μg g−1), limits of detection (2.9–5.1 ng g−1), accuracy (recovery: 85.7–101.7%), and precision (intra-day and inter-day RSDs: 1.68–2.60% and 3.05–4.01%).

The miniaturized molecularly imprinted solid-phase extraction (mini-MISPE) coupled with high-performance liquid chromatography was proposed for the determination of acyclovir in urine. 1.5-mL tapered plastic centrifuge tube filled with hybrid molecularly imprinted polymers (HMIPs) was used as the cartridge of mini-MISPE, and the HMIPs synthesized with 3-aminopropyltriethoxy silane-methacrylic acid as monomer exhibited good recognition and selectivity for acyclovir. Under the optimized condition, good linear calibration was obtained in a range of 0.5–15 μg mL−1 with the correlation coefficient of 0.9994, and the recoveries at three spiked levels were 91.6–103.3% in urine with the relative standard deviation (RSD) of ≤3.5%. Excellent intra-day and inter-day repeatability were achieved with RSD of ≤2.6% and 4.0% in three different concentrations. This method combined the advantages of HMIPs and mini-MISPE, and it could become an alternative tool for analyzing the residues of acyclovir in complex urine matrices.

A novel kind of water-compatible magnetic imprinted cyromazine microsphere (WCMM) was synthesized by water/oil/water suspension polymerization. The obtained WCMM was homogenously spherical with porous morphology and strong magnetic properties. The microspheres were successfully used as adsorbent in dispersive solid-phase extraction (WCMM-dSPE) to selectively extract cyanazine and atrazine from environmental water. Good linearity of the two analytes was observed in the range from 2.5 to 200.0 ng mL −1 . The average recoveries at three spiking levels ranged from 84.8% to 104.3% with relative standard deviations (RSD) less than 6.9%. Compared with magnetic non-imprinted particles (WCMN), the proposed WCMM adsorbent of dSPE efficiently improved the efficiency of extracting cyanazine and atrazine from environmental water samples and eliminated the effect of cyromazine leakage on the quantitative analysis of cyanazine and atrazine. The proposed WCMM-dSPE method combined the advantages of magnetic separation, molecular imprinted microspheres and dSPE.

A simple molecularly imprinted solid-phase extraction coupled with ligand exchange chromatography method was developed for rapid screening of R-(+)- and S-(−)-ofloxaxin in human urine. New molecularly imprinted microspheres (MIMs) were synthesized by aqueous suspension polymerization using pazufloxacin as pseudo template and it showed high affinity and selectivity to ofloxacin in aqueous solution. Baseline separation of ofloxacin enantiomers in human urine were obtained on a C18 column in less than 20 min and no interferences from the protein or endogenous compounds were observed. Under the optimal conditions, good linearity of the method was obtained in the range of 0.07 to 60 µg/mL with the correlation coefficient of r2 ≥ 0.9996 and the relative standard deviation of 2.9–4.5%. The detection limits signal-to-noise ratio of 3 (S/N = 3) was 0.03 µg/mL and 0.04 µg/mL for S-(−)- and R-(+)- ofloxaxin, respectively. The proposed method could be potential applied to investigate the stereoselectivity and pharmac...

In this study, through in-situ polymerization process, a novel composite of attapulgite/hydrophilic molecularly imprinted monolithic resin (AT/HMIMR) were prepared in pipette tips for extraction trace plant growth regulators in cucumbers. In the preparation procedure, fibrillar attapulgite nanoparticles were embedded to increase extraction capacity, polyethyleneglycol-6000 was employed as a dual-function porogen, that acted as both the structure-directing agent of the HMIMR and the attapulgite dispersant. N-(1-naphthyl) ethylenediamine dihydrochloride was used as a dummy template to accurate quantification on extraction procedures. Experimental parameters of AT/HMIMR for extracting plant growth regulators from cucumbers were optimized, and the results showed that the recoveries of ranged from 92.4% to 101.1% with relative standard deviations ≤ 6.5% (n = 3). Considering its microporous monolithic column structure, multiple adsorption mechanism, and specific selectivity, AT/HMIMR shows promise for applications that require specific recognition for the analytes in real complex samples.

With 2,4-dinitrofluorobenzene–acetonitrile pre-column derivatization, taurine and its intermediate (2-aminoethyl hydrogen sulfate) in beverages and milk samples were determined by high-performance liquid chromatography coupled with diode array detection. Chromatographic separation was performed by isocratic reverse phase model with acetonitrile-phosphate solution (pH 7.0) (19: 81, v/v) as the mobile phase on a C18 column. By precipitation protein and filter, the sample could be directly used for precolumn derivatization and detection. Good linearity was observed in a range of 0.4–500 mg/L for all analytes with the correlation coefficients (r2) ≥ 0.9991. Overall recoveries of the two compounds ranged from 82% to 103% with repeatability (RSD) less than 4.6% at three different spiked levels (5 to 200 mg/L, n = 5). The proposed method offered a good alternative for routine analysis due to its simplicity and at the same time reliability.

A fluffy porous ethylenediamine-connected graphene/carbon nanotube composite (EGC), prepared by a simple and time-saving one-pot synthesis, was successfully applied as an adsorbent in pipette-tip solid-phase extraction (PT-SPE) for the rapid extraction and determination of clenbuterol (CLB) from pork. In the one-pot synthesis, carbon nanotubes were inserted into graphene sheets and then connected with ethylenediamine through chemical modification to form a three-dimensional framework structure to prevent agglomeration of the graphene sheets. Under the optimum conditions for extraction and determination, good linearity was achieved for CLB in the range of 15.0-1000.0ngg-1 (r=0.9998) and the recoveries at three spiked levels were in the range of 92.2-96.2% with relative standard deviation ≤9.2% (n=3). In comparison with other adsorbents, including silica, NH2, C18, and Al2O3, EGC showed higher extraction and purification efficiency for CLB from pork samples. This analytical method combines excellent adsorption performance of EGC and high extraction efficiency of PT-SPE.

A water-compatible dummy molecularly imprinted resin (MIR) was synthesized in water using melamine, urea, and formaldehyde as hydrophilic monomers of co-polycondensation. A triblock copolymer (PEO-PPO-PEO, P123) was used as porogen to dredge the network structure of MIR, and N-(1-naphthyl) ethylenediamine dihydrochloride, which has similar shape and size to the target analytes, was the dummy template of molecular imprinting. The obtained MIR was used as the adsorbent in a green miniaturized solid-phase extraction (MIR⬜mini-SPE) of plant growth regulators, and there was no organic solvent used in the entire MIR⬜mini-SPE procedure. The calibration linearity of MIR⬜mini-SPE⬜HPLC method was obtained in a range 5⬜250ngmL(↙1) for IAA, IPA, IBA, and NAA with correlation coefficient (r) Ⱕ0.9998. Recoveries at three spike levels are in the range of 87.6⬜100.0% for coconut juice with relative standard deviations Ⱔ8.1%. The MIR⬜mini-SPE method possesses the advantages of environmental friendliness, simple operation, and high efficiency, so it is potential to apply the green pretreatment strategy to extraction of trace analytes in aqueous samples.

A highly selective molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatography (HPLC) ultraviolet-visible detection was developed for the simultaneous isolation and determination of four Sudan dyes (I, II, III and IV) in catsup products. The novel molecularly imprinted microspheres (MIM) were synthesized by aqueous suspension polymerization using phenylamine and naphthol as template, which showed high affinity to Sudan dyes in aqueous solution. In order to develop a selective extraction protocol for simultaneous determination the four Sudan dyes from catsup products, the molecular recognition properties of MIM as a SPE sorbent were evaluated. Under the optimized condition, good linearity was obtained from 0.01 to 2.5 μg g(-1) (r(2)≥ 0.9990) with the relative standard deviations of less than 3.4%. This proposed MISPE-HPLC procedure eliminated the effect of template leakage on quantitative analysis and could be applied to direct determination of four Sudan dyes in complicated food samples.

A simple method for the extraction and determination of trace imidacloprid in tomatoes was developed using ultrasonic dispersion liquid–liquid microextraction coupled with liquid chromatographic separation. An ultrasonic dispersion process was applied to accelerate the formation of the fine cloudy solution without using disperser solvents, which was markedly increased the extraction efficiency and reduced the equilibrium time. The results revealed that tetrachloroethane as extraction solvent could be directly applied to the filtered tomato juice with the assistance of ultrasonic dispersion. Under the optimum condition, the enrichment factor of imidacloprid could reach 375 folds and the average recovery of samples ranged from 87.6 to 110% with RSD less than 4.5% (n = 3). Compared to the conventional sample pretreatment method, the proposed method had the advantage of short time, simple operation, high sensitivity and low consumption of organic solvent.

Solid-phase extraction (SPE) and reversed-phase liquid chromatography (RP-LC) have been used for simple, sensitive simultaneous analysis of cyromazine and melamine residues in liquid milk and eggs. The conditions used for SPE and LC were investigated and optimized. A combined cation-exchange–reversed-phase cartridge was used for clean-up, and an ODS (C18) column (150 mm × 4.6 mm i.d., 5-μm particles) with 62:38 (v/v) 5 mm sodium lauryl sulfate (pH 3.4)–acetonitrile as mobile phase was used for RP-LC. Under the optimum conditions the method limit of detection (LOD) for both cyromazine and melamine was 6.2 μg kg−1 for liquid milk samples, and 11.5 μg kg−1 for egg samples. Average recovery of cyromazine and melamine from milk samples was 90.3%, RSD 4.6–5.6%, and 99.6%, RSD 3.2–4.7%, respectively. Average recovery of cyromazine and melamine from egg samples was 85.3%, RSD 1.0–4.7%, and 89.6%, RSD 3.1–5.0%, respectively. The method enables detection of melamine and cyromazine at levels as low as 20.7 μg kg−1 in liquid milk and 38.3 μg kg−1 in egg.

A simple on-line molecularly imprinted solid-phase extraction coupled with liquid chromatographic separation was developed for the simultaneous determination of enrofloxacin and its active metabolite ciprofloxacin from urine samples. The molecularly imprinted monolithic columns were synthesized in water-containing systems using norflorxacin as dummy template and methanol–water (5:1, v/v) as porogenic solvent, which reveal high affinity to enrofloxacin and ciprofloxacin in the aqueous environment. Due to the unique porous structure and flow-through channels existing in the network skeleton of the imprinted monolith, urine samples could be injected directly into the imprinted column, proteins and other biological matrix were quickly washed out and the analytes were selectively retained and enriched. Good linearity was obtained from 0.05 to 200 mg L−1 with relative standard deviations less than 3.1%. The recoveries were higher than 87% at three different concentrations and the limit of detection of the method was 0.01 mg L−1. Moreover, by increasing the injection volume, the sensitivity of the method could be further improved.

A new type of molecularly imprinted ionic liquid magnetic microspheres was synthesized by aqueous suspension polymerization, using 4,4'-dichlorobenzhydrol as a dummy template, and 1-allyl-3-ethylimidazolium hexafluorophosphate and methacrylic acid as co-functional monomers. The results of morphology and magnetic property evaluation of the obtained microspheres demonstrated that it was monodispersed spherical, possessed a rough surface, and an outstanding magnetic properties. Binding experiments revealed that it had a substantial adsorption capacity and strong recognition ability to organochlorine pesticides (OCPs) in aqueous solution. Then the microspheres were applied as an adsorbent of magnetic dispersive solid-phase extraction for the selective recognition and rapid determination of OCPs in environmental water. Under the optimum conditions, good linearity of the three types of OCPs (dicofol, tetradifon, and p,p'-dichlorodiphenyldichloroethane) was achieved in the range of 1.0-100 ng/mL (r ≥ 0.9994). The recoveries at three spiking levels ranged from 82.6 to 100.4% with the RSDs less than 6.9%.

A new kind of selective magnetic dispersive solid-phase sorbent based on multiple Fe3O4 nanospheres as the core structure and molecular imprinted material as the shell structure was synthesized with tert-butylamine and 2-chloroaniline as the templates. The obtained multicore-shell-structured sorbent was spherical (diameter distribution 25-90μm) with porous morphologies, thus incorporating strong magnetic properties and specific molecular recognition coupled with rapid adsorption and dynamic equilibrium. The sorbent was applied for rapid and selective screening of clenbuterol (CLB) in bovine urine samples. Good linearity was obtained in the range 1.25-200ngmL(-1) with the average recovery at three spiked levels ranging from 91.4% to 105.3%. The proposed method significantly improved the purification and extraction efficiency of CLB in urine samples and eliminated the effect of template leakage during quantitative analysis.

A simple and time-saving one pot synthesis of magnetic graphene/carbon nanotube composites (M-G/CNTs) was developed that could avoid the tedious drying process of graphite oxide, and G/CNTs were modified by Fe3O4 nanoparticles in the reduction procedure. It contributed to a shorten duration of the synthesis process of M-G/CNTs. The obtained M-G/CNTs were characterized and the results indicated that CNTs and Fe3O4 nanoparticles were served as spacer distributing to the layers of graphene, which was beneficial for enlarging surface area and improving extraction efficiency. Moreover, M-G/CNTs showed good magnetic property and outstanding thermal stability. Then M-G/CNTs were applied as adsorbent of magnetic dispersive solid-phase extraction for rapid extraction and determination of oxytetracycline in sewage water. Under the optimum conditions, good linearity was obtained in the range of 20-800ngmL(-1) and the recoveries were ranged from 95.5% to 112.5% with relative standard deviations less than 5.8%.

The combination of molecularly imprinted polymers (MIPs) and solid phase extraction (SPE) is reviewed. MIPs, which have high selectivity and affinity for a predetermined molecule (template), have been used as sorbents for SPE to selectively isolate analytes from biological, pharmaceutical, and environmental samples. Solid phase extraction with molecularly imprinted polymers (MIP–SPE) is a promising technique which allows specific analytes to be selectively extracted from complex matrices. This survey summarizes the characteristics, development and application of MIP–SPE in recent years. Existed problems and the future direction of MIP–SPE are also discussed.

A micellar electrokinetic chromatography (MEKC) method was developed for the determination of nateglinide in animal plasma by on-line sweeping technique, in which plasma samples were simply deproteinized with acetonitrile, and analyzed with 16 mmol/L NaH2PO4 + 6 mmol/L Na2B4O7 + 60 mmol/L sodium dodecyl sulfate (SDS) (pH 7.14) as the running buffer, a fused-silica capillary as the separation tube, 21 kV as the running voltage and UV detection at 214 nm. Under these conditions, more than 100-fold enrichment of nateglinide was obtained with the good linear relation in the range of nateglinide plasma concentration 0.2–7 mg/L (R = 0.998). The method could be applied successfully to determine trace drugs in clinical analysis.

A simple and selective molecularly imprinted matrix solid-phase dispersion (MI-MSPD) method coupled with high performance liquid chromatography (HPLC) ultraviolet detection was developed for rapid screening of clenbuterol hydrochloride (CH) in chicken samples. The new molecularly imprinted microspheres (MIM) were synthesized by using butylamine and chloroaniline as dummy template with aqueous suspension polymerization and revealed good affinity to CH in aqueous solution. The application of the obtained MIM as sorbent of matrix solid-phase dispersion (MSPD) improved the selectivity of extraction procedure and avoided the effect of template leakage on quantitative analysis. Under the optimized conditions, good linearity of CH was obtained in a range of 0.059–18.30 μg mL−1 with the correlation coefficient (R) of 0.9996. The recoveries of CH at three spiked levels were ranged from 92.0 to 99.1% with the relative standard deviation less than 4.0% (n = 3). The presented MI-MSPD-HPLC method combined the superiority of MIM and MSPD, and therefore could be potentially applied for the determination of CH in complicated biological samples.

A new molecularly imprinted polymer was synthesized using ofloxacin and theophylline as template and methacryclic acid as function monomer and it was employed as a special dispersant of matrix solid-phase dispersion for selective extraction of fluoroquinolones (ofloxacin, ciprofloxacin and enrofloxacin) and xanthine (caffeine and theophylline) from human serum samples. To eliminate the influences of template leaking on quantitative analysis, acetonitrile–trifluoracetic acid (99:1, v/v) was used as the template removing solution. By using water and acetonitrile–trifluoracetic acid (99.5:0.5, v/v) as the washing and elution solvent, respectively, satisfactory recoveries and clean enough chromatogram could obtained. Good linearity of all the analytes was observed in a range of 0.35–150 μg g−1 with the correlation coefficient (r2) ≥ 0.9991. The recoveries of spiked human serum samples were in a range of 89.5–104.0% for fluoroquinolones and xanthine derivatives with RSD less than of 5.0%.

A new pretreatment method, solid-phase extraction combined with dispersive liquid-liquid microextration (SPE-DLLME), was proposed in first time for the determination of clenbuterol (CLB) in porcine tissue samples. The tissue samples were firstly extracted by SPE, then its eluents were used as dispersant of the followed DLLME for further purification and enrichment of CLB. Various parameters (such as the type of SPE sorbent, the type and volume of elution solvent, the type and volume of extractant and dispersant, etc.) that affected the efficiency of the two steps were optimized. Good linearity of CLB was ranged from 0.19 μg/kg to 192 μg/kg with correlation coefficient (r²) of 0.9995. The limit of detection (LOD) was 0.07 μg/kg (S/N=3) and the recoveries at three spiked levels were ranged from 87.9% to 103.6% with the relative standard deviation (RSD) less than 3.9% (n=3). Under the optimized conditions, the enrichment factor (EF) for CLB could up to 62 folds. The presented method that combined the advantages of SPE and DLLME, had higher selectivity than SPE method and was successfully applied to the determination of CLB in tissue samples.

An ofloxacin molecularly imprinted polymer was synthesized and used as a dispersant of matrix solid-phase dispersion for the determination of enrofloxacin and ciprofloxacin in chicken tissue. The selected dispersant shows high affinity to enrofloxacin and ciprofloxacin in aqueous environment and could selectively enrich them from chicken tissue matrix. The extract was sufficiently clean for further chromatographic analysis without interferences from template leakage or chicken tissue matrix. Linearity ranged from 0.03 to 200 microg/g with the correlation coefficient r(2)>0.9993. The recoveries of spiked chicken tissues were in the range of 82.7-96.6% for enrofloxacin and 88.7-102% for ciprofloxacin.

A gas chromatographic method was developed for simultaneous determination of nine pyrethroids (permethrin, transallethrin, beta-cypermethrin, prallethrin, tetramethrin, transfluthrin, cyphenothrin, phenothrin, imiprothrin) in indoor insecticide products using dibutyl phthalate and iso-octyl phthalate as two internal standards. Parameters affecting the extraction and separation efficiency were investigated. Good linear fit curves were obtained in a range of 0.4–900 mg/l with correlation coefficients >0.999. The proposed method was successfully applied for the determination of pyrethroids in mosquito coils and two aerosol products. The recovery of transallethrin in mosquito coils at three spiked levels was 96.8% with relative standard deviation less than 2.7%. The recoveries of transallethrin, tetramethrin, permethrin and cyphenothrin in aerosol products were 97.2%, 96.4%, 94.3%, 94.6% with RSD less than 2.3%, 2.8%, 3.1%, 2.9%, respectively.

A novel highly selective sample cleanup procedure combining molecular imprinting and matrix solid-phase dispersion (MI-MSPD) was developed for the simultaneous isolation of ofloxacin, pefloxacin, norflorxacin, ciprofloxacin, and enrofloxacin in chicken eggs and swine tissues followed by high-performance liquid chromatography with fluorescence detection. The novel ofloxacin imprinted polymers synthesized in water-containing systems show high selectivity for the five fluoroquinolones in aqueous environment and the affinity can be easily adjusted by the pH of solution. Compared with conventional MSPD methods, using MIPs as selective MSPD sorbents, the five fluoroquinolones could be selectively extracted from a biological matrix and all matrix interferences were eliminated simultaneously. The average recoveries of the five fluoroquinolones were ranged from 85.7 to 104.6% for eggs and 86.8 to 102.7% for tissues with relative standard deviations of less than 7.0%. Detection limits for the identification of the five fluoroquinolones in eggs and tissues ranged from 0.05 to 0.09 ng/g.