Novel molecularly imprinted magnetic nanoparticles for the selective extraction of protoberberine alkaloids in herbs and rat plasma

In this work, a novel magnetic nanomaterial functionalized with a molecularly imprinted polymer was prepared for the extraction of protoberberine alkaloids. Molecularly imprinted polymers were made on the surface of Fe₃O₄ nanoparticles by using berberine as template, acetonitrile/water as porogen, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross‐linker. The optimized molar ratio of template/functional monomer was 1:7. The polymeric magnetic nanoparticles were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The stability and adsorption capacity of the molecularly imprinted polymers were investigated. The molecularly imprinted polymers were used as a selective sorbent for the magnetic molecularly imprinted solid‐phase extraction and determination of jatrorrhizine, palmatine, and berberine. Extraction parameters were studied including loading pH, sample volume, stirring speed, and extraction time. Finally, a magnetic molecularly imprinted solid‐phase extraction coupled to high‐performance liquid chromatography method was developed. Under the optimized conditions, the method showed good linear range of 0.1–150 ng/mL for berberine and 0.1–100 ng/mL for jatrorrhizine and palmatine. The limit of detection was 0.01 ng/mL for berberine and 0.02 ng/mL for jatrorrhizine and palmatine. The proposed method has been applied to determine protoberberine alkaloids in Cortex phellodendri and rat plasma samples. The recoveries ranged from 87.33–102.43%, with relative standard deviation less than 4.54% in Cortex phellodendri and from 102.22–111.15% with relative standard deviation less than 4.59% in plasma.     

Computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous determination of six carbamate pesticides from environmental water

The computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous capture of six carbamate pesticides from environmental water are reported in this work. The quantum mechanical computational approach was employed to design the molecularly imprinted polymers with carbofuran as template. The interaction energies between the template molecule and different functional monomers in various solvents were calculated to assist in the selection of the functional monomer and porogen. The optimised molecularly imprinted polymer was subsequently used as a class‐selective sorbent in solid‐phase extraction for pre‐concentration and determination of carbamates from environmental water. The parameters influencing the extraction efficiency of the molecularly imprinted solid‐phase extraction procedure were systematically investigated to facilitate the class‐selective extraction. For the proposed method, linearity was observed over the range of 2–500 ng/mL with the correlation coefficient ranging from 0.9760 to 1.000. The limits of detection ranged from 0.2 to 1.2 ng/mL, and the limit of quantification was 4 ng/mL. These results confirm that computer‐assisted design is an effective evaluation tool for molecularly imprinted polymers synthesis, and that molecularly imprinted solid‐phase extraction can be applied to the simultaneous analysis of carbamates in environmental water.     

Preparation of magnetic molecularly imprinted polymer for dispersive solid‐phase extraction of valsartan and its determination by high‐performance liquid chromatography: Box‐Behnken design

In this work, core/shell magnetic molecularly imprinted polymer nanoparticles were synthesized for extraction and pre‐concentration of valsartan from different samples and then it was measured with high‐performance liquid chromatography. For preparation of molecularly imprinted polymer nanoparticles, Fe₃O₄ nanoparticles were coated with tetraethyl orthosilicate and then functionalized with 3‐(trimethoxysilyl) propyl methacrylate. In the next step, molecularly imprinted polymer nanoparticles were synthesized under reflux and distillation conditions via polymerization of methacrylic acid, valsartan (as a template), azobisisobutyronitrile and ethylene glycol dimethacrylate as cross linking. The properties of molecularly imprinted polymer nanoparticle were investigated by FTIR spectroscopy, field emission scanning electron microscopy, and X‐ray diffraction. Box‐Behnken design with the aid of desirability function was used for optimizing the effect of variables such as the amounts of molecularly imprinted polymer nanoparticles, time of sonication, pH, and volume of methanol on the extraction percentage of valsartan. According to the obtained results, the affecting variables extraction condition were set as 10 mg of adsorbent, 16 min for sonication, pH = 5.5 and 0.6 mL methanol. The obtained linear response (r² > 0.995) was in the range of 0.005–10 µg/mL with detection limit 0.0012 µg/mLand extraction recovery was in the range of 92–95% with standard deviation less than 6% (n = 3).     

Molecularly imprinted polymeric stir bar: Preparation and application for the determination of naftopidil in plasma and urine samples

In this study, molecularly imprinting technology and stir bar absorption technology were combined to develop a microextraction approach based on a molecularly imprinted polymeric stir bar. The molecularly imprinted polymer stir bar has a high performance, is specific, economical, and simple to prepare. The obtained naftopidil‐imprinted polymer‐coated bars could simultaneously agitate and adsorb naftopidil in the sample solution. The ratio of template/monomer/cross‐linker and conditions of template removal were optimized to prepare a stir bar with highly efficient adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, selectivity, and extraction capacity experiments showed that the molecularly imprinted polymer stir bar was prepared successfully. To utilize the molecularly imprinted polymer stir bar for the determination of naftopidil in complex body fluid matrices, the extraction time, stirring speed, eluent, and elution time were optimized. The limits of detection of naftopidil in plasma and urine sample were 7.5 and 4.0 ng/mL, respectively, and the recoveries were in the range of 90–112%. The within‐run precision and between‐run precision were acceptable (relative standard deviation <7%). These data demonstrated that the molecularly imprinted polymeric stir bar based microextraction with high‐performance liquid chromatography was a convenient, rapid, efficient, and specific method for the precise determination of trace naftopidil in clinical analysis.     

Molecularly imprinted solid-phase extraction for the selective determination of bromhexine in human serum and urine with high performance liquid chromatography

In this work, a novel method is described for the determination of bromhexine in biological fluids using molecularly imprinted solid-phase extraction as the sample cleanup technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and bromhexine as the template molecule. The novel imprinted polymer was used as a solid-phase extraction sorbent for the extraction of bromhexine from human serum and urine. Various parameters affecting the extraction efficiency of the polymer have been evaluated. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning 1 mL methanol and 1 mL of deionized water at neutral pH, loading of 5 mL of the water sample (25 μg L⁻¹) at pH 6.0, washing using 2 mL acetonitrile/acetone (1/4, v/v) and elution with 3× 1 mL methanol/acetic acid (10/1, v/v). The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of bromhexine. Results from the HPLC analyses showed that the calibration curve of bromhexine using MIP from human serum and urine is linear in the ranges of 0.5-100 and 1.5-100 μg L⁻¹ with good precisions (3.3% and 2.8% for 5.0 μg L⁻¹), respectively. The recoveries for serum and urine samples were higher than 92%.     

Highly selective separation and detection of cyromazine from seawater using graphene oxide based molecularly imprinted solid‐phase extraction

A novel molecularly imprinted polymer based on graphene oxide was prepared as a solid‐phase extraction adsorbent for the selective adsorption and extraction of cyromazine from seawater samples. The obtained graphene oxide molecularly imprinted polymer and non‐imprinted polymer were nanoparticles and characterized by scanning electron microscopy. The imprinted polymer showed higher adsorption capacity and better selectivity than non‐imprinted polymer, and the maximum adsorption capacity was 14.5 mg/g. The optimal washing and elution solvents for molecularly imprinted solid phase extraction procedure were 2 mL of acetonitrile/water (80:20, v/v) and methanol/acetic acid (70:30, v/v), respectively. The recoveries of cyromazine in the spiked seawater samples were in the range of 90.3–104.1%, and the relative standard deviation was <5% (n = 3) under the optimal procedure and detection conditions. The limit of detection of the proposed method was 0.7 μg/L, and the limit of quantitation was 2.3 μg/L. Moreover, the imprinted polymer could keep high adsorption capacity for cyromazine after being reused six times at least. Finally, the synthesized graphene oxide molecularly imprinted polymer was successfully used as a satisfied sorbent for high selectivity separation and detection of cyromazine from seawater coupled with high‐performance liquid chromatography.     

Determination of domoic acid in shellfish extracted by molecularly imprinted polymers

A selective sample cleanup method using molecularly imprinted polymers was developed for the separation of domoic acid (a shellfish toxin) from shellfish samples. The molecularly imprinted polymers for domoic acid was prepared by emulsion polymerization using 1,3,5‐pentanetricarboxylic acid as the template molecule, 4‐vinyl pyridine as the functional monomer, ethylene glycol dimethacrylate as the crosslinker, and Span80/Tween‐80 (1:1 v/v) as the composite emulsifiers. The molecularly imprinted polymer showed high affinity to domoic acid with a dissociation constant of 13.5 μg/mL and apparent maximum adsorption capacity of 1249 μg/g. They were used as a selective sorbent for the detection of domoic acid from seafood samples coupled with high‐performance liquid chromatography. The detection limit of 0.17 μg/g was lower than the maximum level permitted by several authorities. The mean recoveries of domoic acid from clam samples were 93.0–98.7%. It was demonstrated that the proposed method could be applied to the determination of domoic acid from shellfish samples.     

Molecularly imprinted solid-phase extraction coupled with HPLC for the selective determination of monobutyl phthalate in bottled water

A molecularly imprinted polymer (MIP) was prepared using monobutyl phthalate as template. The synthesis was optimized by using different porogens and functional monomers. The MIP was used as a selective sorbent in molecularly imprinted solid-phase extraction (MIP-SPE) for pre-concentration and determination of monobutyl phthalate (mBP) from the bottled water. The difference in recognition selectivity of the polymer columns was observed in HPLC system, and the effect of the mobile phase on the performance of MIP columns was also investigated. Control of the MIP-SPE process is seen as important in helping to facilitate the selective extraction of mBP from water samples. Thereafter, the choice of washing solvent, eluting solvent amount, pH of loading sample, flow rate of loading solution and the loading sample volume was presented. The optimized procedure was described as follows: 25 mL spiked aqueous solution was percolated through the MIP-SPE cartridge at the flow rate of 1.5 mL/min. After rinsing with acetonitrile/methanol mixture (1:1, v/v), the bound analyte was desorbed with 3 mL methanol. The developed MIP-SPE method was demonstrated to be applicable for the analysis of mBP in the bottled water.     

A new molecularly imprinted polymer for selective extraction and pre‐concentration of guaifenesin in different samples: Adsorption studies and kinetic modeling

This paper describes the synthesis of a molecularly imprinted polymer by chemical oxidation of pyrrole as the functional monomer, and at the presence of guaifenesin as the template. The prepared polymer was used as adsorbent in molecularly imprinted solid‐phase extraction followed by spectrophotometric determination. Different parameters in the solid‐phase extraction including sample pH, adsorbent weight, washing solution, and elution solvent were studied to determine optimum conditions for isolation and enrichment of guaifenesin. The results showed guaifenesin was quantitatively adsorbed on the molecularly imprinted polymer at pH 6.0 and completely eluted with an ethanol–water solution (50% v/v). An enrichment factor of four with satisfactory recoveries (87.0–95.0%) was obtained. The solid‐phase extraction columns could be used for up to six consecutive elution‐loading cycles without significant decreases in the analyte recoveries. The method had a dynamic range of 3.0 × 10^?6–1.5 × 10^?4 mol/L with a limit of detection and limit of quantification of 1.4×10^?6 and 4.5×10^?6 mol/L, respectively. The proposed procedure was used for the extraction and determination of guaifenesin in different pharmaceutical formulations, with satisfying results being achieved.     

The use of coenzyme Q0 as a template in the development of a molecularly imprinted polymer for the selective recognition of coenzyme Q10

In this work, a novel molecularly imprinted polymer (MIP) for use as a solid phase extraction sorbent was developed for the determination of coenzyme Q10 (CoQ10) in liver extract. CoQ10 is an essential cofactor in mitochondrial oxidative phosphorylation and a powerful antioxidant agent found in low concentrations in biological samples. This fact and its high hydrophobicity make the analysis of CoQ10 technically challenging. Accordingly, a MIP was synthesised using coenzyme Q0 as the template, methacrylic acid as the functional monomer, acetonitrile as the porogen, ethylene glycol dimethacrylate as the crosslinker and benzoyl peroxide as the initiator. Various parameters affecting the polymer preparation and extraction efficiency were evaluated. Morphological characterisation of the MIP and its proper comparison with C18 as a sorbent in solid phase extraction were performed. The optimal conditions for the molecularly imprinted solid phase extraction (MISPE) consisted of 400 μL of sample mixed with 30 mg of MIP and 600 μL of water to reach the optimum solution loading. The loading was followed by a washing step consisting of 1 mL of a 1-propanol solution (1-propanol:water, 30:70,v/v) and elution with 1 mL of 1-propanol. After clean-up, the CoQ10 in the samples was analysed by high performance liquid chromatography. The extraction recoveries were higher than 73.7% with good precision (3.6–8.3%). The limits of detection and quantification were 2.4 and 7.5 μg g⁻¹, respectively, and a linear range between 7.5 and 150 μg g⁻¹ of tissue was achieved. The new MISPE procedure provided a successful clean-up for the determination of CoQ10 in a complex matrix.     

Molecularly imprinted solid-phase extraction for the selective HPLC determination of ractopamine in pig urine

A method was developed for the determination of ractopamine in pig urine using molecularly imprinted solid-phase extraction (MISPE) as the sample clean-up technique combined with high-performance liquid chromatography. The molecularly imprinted polymer (MIP) was synthesized in acetonitrile-triethylamine system using ractopamine (RAC) as the template and acrylamide as the monomer. The binding capacity of the polymer toward RAC was found to be about 2.57 mg of ractopamine/g of polymer. The optimal procedures for MISPE consisted of conditioning with 3 mL methanol, equilibrating with 3 mL of water, loading volume of <10 mL of aqueous sample (pH 7), washing with 3 mL water and 3 mL methanol, and eluting with 5 mL of 5% ammonia in methanol. In the four spiked samples with the levels of 0.01, 0.1, 1.0 and 5.0 μg/mL, the mean recoveries of analyte on the MIP were higher than 90% with relative standard deviation <10%, and significant differences between imprinted and non-imprinted materials were observed. The MIP selectivity was evaluated by checking 11 drugs with similar and different molecular structures to that of RAC. The characteristics of three-dimensional cavities and hydrogen bond interaction were regarded as the main factors that dominated the retention of RAC on the MISPE cartridge.     

Molecularly imprinted polymer with high-fidelity binding sites for the selective extraction of barbiturates from human urine

In this paper we describe the synthesis of a molecularly imprinted polymer (MIP) by precipitation polymerisation, with barbital as the template molecule, and the application of the barbital MIP as a molecularly selective sorbent in the solid-phase extraction (SPE) of barbiturates from human urine samples. The MIP was synthesised by precipitation polymerisation using 2,6-bis-acrylamidopyridine as the functional monomer and DVB-80 as the cross-linking agent. The spherical MIP particles produced were 4.2 ± 0.4 μm in diameter; a non-imprinted control polymer (NIP) in bead form was 4.8 ± 0.4 μm (mean±standard deviation) in diameter. The particles were packed into a solid-phase extraction cartridge and employed as a novel sorbent in a molecularly imprinted solid-phase extraction (MISPE) protocol. The MIP showed high selectivity for the template molecule, barbital, a feature which can be ascribed to the high-fidelity binding sites present in the MIP which arose from the use of 2,6-bis-acrylamidopyridine as the functional monomer. However, the MIP also displayed useful cross-selectivity for other barbiturates besides barbital. For real samples, the MIP was applied for the extraction of four barbiturates from human urine. However, due to the high urea concentration in this sample which interfere the proper interaction of barbiturates onto the MIP, a tandem system using a commercially available sorbent was developed.     

A new molecularly imprinted polymer for selective extraction of cotinine from urine samples by solid-phase extraction

Cotinine, the main metabolite of nicotine in human body, is widely used as a biomarker for assessment of direct or passive exposure to tobacco smoke. A method for molecularly imprinted solid-phase extraction (MISPE) of cotinine from human urine has been investigated. The molecularly imprinted polymer (MIP) with good selectivity and affinity for cotinine was synthesized using cotinine as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The imprinted polymer was evaluated for use as a SPE sorbent, in tests with aqueous standards, by comparing recovery data obtained using the imprinted form of the polymer and a non-imprinted form (NIP). Extraction from the aqueous solutions resulted in more than 80% recovery. A range of linearity for cotinine between 0.05 and 5 μg mL⁻¹ was obtained by loading 1 mL blank urine samples spiked with cotinine at different concentrations in acetate buffer of pH 9.0, and by using double basic washing and acidic elution. The intra-day coefficient of variation (CV) was below 7% and inter-day CV was below 10%. This investigation has provided a reliable MISPE–HPLC method for determination of cotinine in human urine from both active smokers and passive smokers. Figure     

Magnetic molecularly imprinted polymer for the efficient and selective preconcentration of diazinon before its determination by high‐performance liquid chromatography

A molecularly imprinted polymer was selectively applied for solid‐phase extraction and diazinon residues enrichment before high‐performance liquid chromatography. Diazinon was thermally copolymerized with Fe₃O₄@polyethyleneglycol nanoparticles, methacrylic acid (functional monomer), 2‐hydroxyethyl methacrylate (co‐monomer), and ethylene glycol dimethacrylate (cross‐linking monomer) in the presence of acetonitrile (porogen) and 2,2‐azobisisobutyronitrile (initiator). Then, the imprinted diazinon was reproducibly eluted with methanol/acetic acid (9:1, v/v). The sorbent particles were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The comprehensive study of variables through experimental design showed that the maximum performance was achieved under these conditions: pH 7, 10 mL sample volume, 15 mg sorbent, 10 min vortex time, 5 min ultrasonic time, 200 μL methanol/acetic acid (9:1, v/v) as eluent, and 5 min desorption time. Under optimized conditions, the molecularly imprinted polymer solid‐phase extraction method demonstrated a linear range (0.02–5 g/mL), a correlation coefficient of 0.997, and 0.005 g/mL detection limit.     

Preparation and application of molecularly imprinted polymer solid‐phase microextraction fiber for the selective analysis of auxins in tobacco

As signal molecules, auxins play an important role in mediating plant growth. Due to serious interfering substances in plants, it is difficult to accurately detect auxins with traditional solid‐phase extraction methods. To improve the selectivity of sample pretreatment, a novel molecularly imprinted polymer ‐coated solid‐phase microextraction fiber, which could be coupled directly to high‐performance liquid chromatography, was prepared with indole acetic acid as template molecule for the selective extraction of auxins. The factors influencing the polymer formation, such as polymerization solvent, cross‐linker, and polymerization time, were investigated in detail to enhance the performance of indole acetic acid‐molecularly imprinted polymer coating. The morphological and chemical stability of this molecularly imprinted polymer‐coated fiber was characterized by scanning electron microscopy, infrared spectrometry, and thermal analysis. The extraction capacity of the molecularly imprinted polymer‐coated solid‐phase microextraction fiber was evaluated for the selective extraction of indole acetic acid and indole‐3‐pyruvic acid followed by high‐performance liquid chromatography analysis. The linear range for indole acetic acid and indole‐3‐pyruvic acid was 1–100 µg/L and their detection limit was 0.5 µg/L. The method was applied to the simultaneous determination of two auxins in two kinds of tobacco (Nicotiana tabacum L and Nicotiana rustica L) samples, with recoveries range from 82.1 to 120.6%.     

Response surface methodology approach for the preparation of a molecularly imprinted polymer for solid‐phase extraction of fenoxycarb pesticide in mussels

The aim of this work was to develop an efficient method for the selective extraction and analysis of fenoxycarb, a carbamate pesticide, in mussel samples using a molecularly imprinted solid‐phase extraction device. The optimization of molecularly imprinted polymer synthesis was performed using the experimental design under the response surface methodology approach. A fast rebinding study and Freundlich isotherm adsorption were carried out to calculate binding capacity B, site number n, and affinity constant K_f. The optimum molecularly imprinted polymer was successfully used as sorbent of a solid‐phase extraction cartridge for the determination of fenoxycarb in real mussel samples. The range of linearity was 0.3–30 mg/L with a correlation coefficient of 0.991. The limit of detection was 0.247 mg/kg. The recovery of fenoxycarb extracted from mussel samples of Mediterranean sea was 97% (n = 3) with relative standard deviation between 6 and 7% proving the reliability of the developed method.     

Extraction of Anthraquinones from Rhubarb by a Molecularly Imprinted–Matrix Solid-Phase Dispersion Method with HPLC Detection

A simple method based on matrix solid-phase dispersion for selective extraction of anthraquinones from rhubarb samples was developed using a molecularly imprinted polymer as sorbent. The molecularly imprinted polymer was prepared using emodin as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking agent. The polymer was characterized by scanning electron microscopy and Fourier-transform infrared spectrometry. Isothermal adsorption and dynamic adsorption experiments were performed. The best extraction conditions for anthraquinones were obtained at a ratio of molecularly imprinted polymer to sample of 1:1, a dispersion time of 5 minutes, with 5% aqueous methanol as the washing solvent, and an elution solvent of methanol-acetic acid (99:1, v/v). Once the matrix solid-phase dispersion process was optimized, the extract was reacted with 8% hydrochloric acid for hydrolysis. The anthraquinones extracted from rhubarb were determined by liquid chromatography. The detection limits of chrysophanol, emodin, physcion, and aloe-emodin were 0.23, 0.24, 0.28, and 0.27 µg mL^?1, respectively. The proposed method was compared with the method in Chinese pharmacopoeia, and the results show that the extraction yield of anthraquinones obtained by molecularly imprinted polymer–matrix solid-phase dispersion method was higher. Moreover, the proposed method is faster and simpler and can achieve extraction and purification in the same system.     

Selective solid‐phase extraction using a molecularly imprinted polymer for the analysis of patulin in apple‐based foods

The aim of this work was to evaluate the use of a molecularly imprinted polymer as a selective solid‐phase extraction sorbent for the clean‐up and pre‐concentration of patulin from apple‐based food products. Ultra high pressure liquid chromatography coupled to ultraviolet absorbance detection was used for the analysis of patulin. The molecularly imprinted polymer was applied, for the first time, to the determination of patulin in apple juice, puree and jam samples spiked within the maximum levels specified by the European Commission No. 1881/2006. High recoveries (>77%) were obtained. The method was validated and found to be linear in the range 2–100 μg/kg with correlation coefficients greater than 0.965 and repeatability relative standard deviation below 11% in all cases. Compared with dispersive solid‐phase extraction (QuEChERS method) and octadecyl sorbent, the molecularly imprinted polymer showed higher recoveries and selectivity for patulin. The application of Affinisep molecularly imprinted polymer as a selective sorbent material for detection of patulin fulfilled the method performance criteria required by the Commission Regulation No. 401/2006, demonstrating the suitability of the technique for the control of patulin at low ppb levels in different apple‐based foods such as juice, puree and jam samples.     

One‐pot synthesis of a multi‐template molecularly imprinted polymer for the extraction of six sulfonamide residues from milk before high‐performance liquid chromatography with diode array detection

A highly selective molecularly imprinted polymer sorbent was synthesized and employed for the simultaneous determination of six sulfonamide antibiotic residues (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, and sulfamethizole) in milk samples. Multi‐analyte imprinted particles were used as a sorbent in solid‐phase extraction. Sulfonamides were separated on a high‐performance liquid chromatography column (Merck–Lichrospher RP18e, 5 μm 250 × 4 mm) and further identified and quantified by diode array detection. Several parameters including required loading of the molecularly imprinted polymer sorbent, mass of milk, volume, and type of elution solvent, as well as time for absorption and elution were investigated to obtain optimal experimental conditions. For comparison purpose, a non‐imprinted polymer was applied under the optimum conditions. The validation study according to the European Union Decision 2002/657/EC was based on the investigation of linearity, selectivity, stability, limits of detection and quantitation, decision limit, detection capability, trueness, precision, and ruggedness according to Youden's approach. The decision limit and detection capability values in the milk were achieved from 101.9 to 113.5 μg/kg and from 114.4 to 135.4 μg/kg, respectively, depending on the target sulfonamide drug. Finally, the optimized protocol was successfully applied to commercial milk samples and human breast milk.     

Determination of macrolide antibiotics residues in pork using molecularly imprinted dispersive solid‐phase extraction coupled with LC–MS/MS

A class‐specific macrolide molecularly imprinted polymer was synthesized by precipitation polymerization using tulathromycin as the template and methacrylic acid as the functional monomer. The polymers revealed different specific adsorption and imprinting factor for macrolides with different spatial arrangement of side chains as well as lactonic ring size. And the molecularly imprinted polymer possessed maximum adsorption capacity (54.1 mg/g) and highest imprinting factor (2.4) toward 15‐membered ring azithromycin. On the basis of molecularly imprinted polymer dispersive solid‐phase extraction, a rapid, selective, and reproducible method for simultaneous determination of seven macrolide antibiotics residues in pork was established by using liquid chromatography with tandem mass spectrometry. At spiking levels of 5, 10, 25, and 100 μg/kg, average recoveries of seven macrolides ranged from 68.6 to 95.5% with intraday and interday relative standard deviations below 8%. The limits of detection and limits of quantification were 0.2–0.5 and 0.5–2.0 μg/kg, respectively.