A vortex-assisted liquid-liquid microextraction method combined with high performance liquid chromatography-diode array detector has been developed for the determination of parabens in foods, cosmetics and pharmaceutical products. In this work, polymeric deep eutectic solvents composed of DL-menthol and polyethylene glycol with three different light grades were prepared successfully for the first time and used as extraction solvents. The influencing parameters on the extraction efficiency including type of extraction solvent, salt addition, composition of deep eutectic solvent, volume of extraction solvent, extraction time and solution pH were evaluated. Under the optimized conditions, using DL-menthol and polyethylene glycol 400 at a molar ratio of 1:1 as the extraction solvent, the method exhibited good linearity with linear coefficients greater than 0.9995. Limits of detection and limits of quantification were in the range of 0.3-2 ng mL-1 and 1-5 ng mL-1, respectively. The proposed method was successfully applied to determine four parabens in seven commercial products. The proposed method is simple, green and efficient, and could be applied to determine parabens in complex matrices.

A novel method for the determination of aflatoxins B1, B2, G1, and G2 (AFB1, AFB2, AFG1, AFG2) in animal feed samples based on magnetic solid-phase cleanup and novel pre-column derivatization has been developed. In this work, synthesized polyvinylpyrrolidone-coated Fe3O4 magnetic nanoparticles were applied as adsorbents for rapid cleanup for extracts of animal feed samples. The purified extract was then derivatized with trifluoroacetic acid coupling ultraviolet irradiation which enabled the weakly fluorescent AFB1 and AFG1 transformed into their highly fluorescent hemiacetals derivatives. Afterward aflatoxins were separated and quantified by reverse phase liquid chromatography with fluorescence detection. The results indicated that four AFs presented excellent linear response with correlation coefficients > 0.996 and recoveries ranged from 86.7 to 108.9% with relative standard deviations (RSDs) from 3.6 to 6.4%. The limits of detection (LODs) were 0.0392, 0.2429, 0.0842, 0.4556 ng mL-1 for AFB1, AFB2, AFG1 and AFG2, respectively.

In this study, an in situ deep eutectic solvent-liquid-liquid microextraction method together with high performance liquid chromatography was developed for the determination of parabens in aqueous sample. The hydrophobic deep eutectic solvent, formed in situ by the DL-menthol and decanoic acid was used as the extraction solvent. Various parameters affecting the extraction efficiency including the composition of deep eutectic solvent, temperature of sample solution, extraction time, solution pH and salt concentration were investigated and optimized. Under the optimum conditions, the linear range of calibration curves was in the range of 3-1000 ng mL-1. The limits of detection and limits of quantification were in the range of 0.6-0.8 and 2.0-2.5 ng mL-1, respectively. The relative standard deviations were less than 7.2% for both intra-day and inter-days analysis. Finally, the proposed method was successfully applied to determine four parabens in environmental water samples with acceptable recoveries.