Preparation of stoichiometric molecularly imprinted polymer coatings on magnetic particles for the selective extraction of auramine O from water.

A novel magnetic molecularly imprinted polymer for the selective recognition of auramine O was rationally designed via screening from a library of nonimprinted polymers. A stoichiometric ratio of functional monomer (itaconic acid) and template molecule (auramine O) was found to be 1.5. Meanwhile, the synthesized SiO2 @Fe3 O4 was modified by 0.5 mol/L hydrochloric acid to facilitate the preparation of magnetic molecularly imprinted polymer particles. Adsorption experiments showed that the magnetic polymer particles exhibited good selectivity, recoveries, and enrichment performance. The stoichiometric imprinted polymers have been employed for the selective preconcentration of auramine O from lake water sample. The high specificity of the stoichiometric imprinted polymers was proven in the extraction of mixture solution of auramine O, auramine O hydrochloride, and chrysoidine, and the recoveries ranged between 99.66 and 108.75% (RSD 2.6-3.7%, n = 3) for lake water. These results suggest that this method is effective and can be successfully applied to the analysis of auramine O in environmental water samples.

Novel carrier-mediated membrane-assisted three-phase liquid-liquid extraction coupled with liquid chromatography-mass spectrometry for the determination of eight biogenic amines in foods.

Analysis of biogenic amines (BAs) is of great importance due to their toxicity and usage as indicators of food freshness. In this study, membrane-assisted three-phase liquid-liquid extraction (MA-3pLLE) was proposed to integrate extraction and back-extraction into a single step using a specially designed U-shaped device. Parameters affecting the performance of the extraction method were optimized. Coupled with liquid chromatography-mass spectrometry, the method was successfully applied for the simultaneous determination of eight BAs without derivatization in apple juice, orange juice, red wine, soy sauce and milk granules, with satisfactory recoveries and RSDs. The calibration curve of the method was linear in the range of 1.00~100.00 ng/mL, with a correlation coefficient (r2) ≥ 0.9908. The limits of detection were in the range of 0.03~1.00 ng/mL. MA-3pLLE is efficient, reproducible, and green and has great potential for application in the one-step extraction of analytes from complex matrices.

Membrane-Protected Molecularly Imprinted Polymer for the Microextraction of Indole-3-butyric Acid in Mung Bean Sprouts.

Based on the hollow fiber protected molecularly imprinted polymer, a micro-solid-phase extraction (µ-SPE) method was developed and applied for the analysis of indole-3-butyric acid in mung bean sprouts by high-performance liquid chromatography. The extraction conditions of the µ-SPE method were optimized using L9(34) orthogonal, and optimum conditions were found as follows: pH of sample solution was 2.0, chloroform was the organic solvent for embedding the µ-SPE bars, and acetonitrile was the desorption solvent. In addition, the extraction time was 80 min, desorption time was 5 min, stirring speed was 800 rpm, and concentration of NaCl was 10%. Under the optimum conditions, a standard curve was established for IBA, with a correlation coefficient of 0.9999. After extraction with phosphate buffer solution (pH = 9.0), successful pretreatment of mung bean sprouts was achieved by the µ-SPE method. The limit of detection was 0.075 mg/kg, and the recoveries were found to be in the range of 88.9-106.4%. This method is simple, environmentally friendly, and can be used for the determination of indole auxin contents in green bean sprouts quickly and accurately.