Specific molecularly imprinted membranes (MIMs) for pyrethroid insecticides were developed and characterized for the first time in this study by cold plasma-induced grafting polymerization using methacrylic acid as a functional monomer and cypermethrin (CYP) as a template. The nonimprinted membranes (NIMs) were also synthesized using the same procedure without the template. Meanwhile, AFM, XPS, ATR-FTIR, contact angle, and permselectivity experiments were conducted to elucidate the imprinting and recognition properties of MIMs. Results demonstrated that MIMs exhibited excellent imprinting effect and high permselectivity. A molecularly imprinted-membrane-assisted solvent extraction (MI-MASE) method based on the MIMs was established. The operating conditions were optimized for group-selective extraction of the five pyrethroid insecticides. Compared with NIMs, higher extraction recoveries (83.8% to 100.6%) of the five pyrethroid insecticides by gas chromatography-electron capture detector (GC-ECD) were obtained using MIMs at three spiked levels in fish samples; the RSD values were lower than 8.3%. The limits of detection (LOD) and quantification (LOQ) defined as the concentrations at which the signal-to-noise (S/N) ratio is 3:1 and 10:1, respectively, were in the range of 0.26 to 0.42 μg/kg and 0.77 to 1.27 μg/kg, respectively. No matrix effect of the developed MI-MASE was observed by gas chromatography/tandem mass spectrometry (GC/MS/MS). These results demonstrated a highly selective, efficient, and environment-friendly MI-MASE technique for preconcentration and purification of pyrethroid insecticides from seafood, followed by GC-ECD and GC/MS/MS. The excellent applicability and potential of MI-MASE for routine monitoring of pyrethroid pesticides in food samples has also been confirmed.
A novel polystyrene/pyridine composite nanofiber was synthesized and utilized as the sorbent material for the solid‐phase extraction of bisphenol A and five common phthalate esters in milk. The method of extraction integrated extraction and preconcentration of target analytes into a single step. Bisphenol A and five common phthalate esters were selected as target compounds for the development and evaluation of the method. The effects of operating parameters for nanofiber‐based solid‐phase extraction, such as selection and amount of sorbent, the volume fraction of perchlorate (precipitate protein), desorption solvent, volume of desorption solvent, and effect of salt addition were optimized. Under optimal conditions, higher extraction recoveries (89.6–118.0%) of the six compounds in milk spiked at three levels were obtained, and the satisfied relative standard deviation were ranged from 0.6 to 10.9%. The detection limits and quantification limits of the method ranged from 0.01 to 0.06 μg/L and 0.05 to 0.53 μg/L, respectively. Matrix effects were also verified and well controlled in the range of 91.3–109.3%. The new method gave better performance metrics than Chinese standard method and other published methods. Thus, the proposed method may be applied to the analysis of the phthalate esters and bisphenol A in complex matrixes.
Packed-nanofiber solid phase extraction (PFSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the simultaneous determination of five phthalate esters (PAEs) and bisphenol A (BPA) in fruit juice. The PAEs and BPA was concentrated by PFSPE using polystyrene- pyridine (PS-PD) nanofibers as the sorbent, followed determined by GC-FID. Under this modified procedure, satisfied recoveries in fruit juice sample ranging from 81.9% to 109.6% were obtained. And relative standard deviation values (RSD) were ranged from 1.9 % to 9.8% in orange juice sample. The limits of detection (LOD) and the limits of quantification (LOQ) of five PAEs and BPA were ranged from 0.02 μg/mL to 0.30 μg/mL and 0.06 μg/L to 1.10 μg/L, respectively. This established method was successfully applied to detect real fruit juice samples, which were collected in local supermarket. These results demonstrated the applicability of the established PFSPE-based extraction coupled with gas chromatography method for determination of PAEs and BPA in fruit juice products.
The detection of vitamin D in complex samples is challenging because of the instability of vitamin D in sample preparation. To resolve this problem, packed-fiber solid-phase extraction (PFSPE) has been successfully developed for the pre-treatment of samples containing vitamin D 2 (D 2) and vitamin D 3 (D 3) in dairy products. Based on PFSPE, vitamin D could avoid oxidation because of the shorter extraction time. The adsorbent materials, polystyrene/polypyrrole (PS/PPy) nanofibers, were prepared by electrospinning of PS and in situ polymerization of PPy on the surface of PS nanofibers. The linearity was within the range of 1-2000 ng mL −1 in dairy solution, and the recoveries were 91.9-109.1% with a relative standard deviation (RSD) < 13.6%. Therefore, the prepared method could be used for the detection of D 2 and D 3 in dairy products.
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