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A novel and rapid low-density solvent-based dispersive liquid-liquid microextraction technique combined with magnetic solid-phase extraction (MSPE) was developed for preconcentration and separation of synthetic phenolic antioxidants (SPAs) in vegetable oils prior to high-performance liquid chromatography. 1-Heptanol was used as extractant and decanoic acid@Fe3O4 nanoparticles (DA@Fe3O4 NPs) as carrier to retrieve and separate the 1-heptanol. In that manner, the upper extractant containing the SPAs is the target of the MSPE step rather than the SPAs directly. Thanks to the interaction between carboxyl group present on the surface of the magnetic nanoparticles and the alcohol functional group of the extractant, the DA@Fe3O4 NPs facilitates the recollection of the 1-heptanol after extraction. The main parameters affecting the extraction recoveries of four SPAs were investigated, and the proposed method provided a good linearity in the range of 50-2000 ng mL−1, low limits of detection (1.2-5.8 ng mL−1), and good repeatability of the extractions (relative standard deviations ≤6.7%, n = 5), and recoveries were ranged from 90.2% to 99.5%. [ABSTRACT FROM AUTHOR]

A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. [ABSTRACT FROM AUTHOR]

In the present study, an extraction, preconcentration, and determination method has been reported for some synthetic phenolic antioxidants and bisphenol A in honey samples using dispersive liquid-liquid microextraction technique followed by gas chromatography-flame ionization detection. The main factors influencing the extraction efficiency including extractive solvent type and volume as well as the volume of dispersive solvent, salt addition, and pH are evaluated in this study. Under the optimum extraction conditions, limits of detection and quantification for all target analytes were obtained in the ranges of 0.4-4.7 and 1.3-14 ng g, respectively. Enrichment factors and extraction recoveries were in the ranges of 144-186 and 72-93 %, respectively. The method precision was evaluated at 100 ng g of each analyte, and the relative standard deviations were found to be less than 7.6 % for intra-day ( n = 6) and less than 8.3 % for inter-days ( n = 4). The proposed method has been successfully applied to the analysis of different honey samples and two analytes, butylated hydroxytoluene and butylated hydroxyanisole, were determined at nanogram per gram level in one honey sample. [ABSTRACT FROM AUTHOR]

Abstract: A simple, rapid and sensitive sample pretreatment technique, termed dispersive liquid–liquid microextraction (DLLME), was developed as an extraction methodology to determine two synthetic phenolic antioxidants (SPAs), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), in various fruit juice samples prior to high performance liquid chromatography (HPLC). The extraction method is based on replacing the extraction solvent in the ordinary DLLME, namely the chlorinated organic solvent, with low-density organic solvents such as hexane, ethyl acetate, octanol and 2-ethyl-1-hexanol in the ternary component solvent (aqueous solution:extracting solvent:disperser solvent) system. Several factors affecting the microextraction efficiency, such as type and volume of extraction and dispersive solvents, pH of the sample solution, extraction time, ionic strength and extraction temperature, were investigated. Under the optimum conditions, the method yielded a linear calibration curve ranging from 10 to 2500μgL−1 for BHA and 2 to 2500μgL−1 for BHT, with determination coefficients (R 2) varying from 0.9993 to 0.9989. Enrichment factors for BHA and BHT were 208 and 203, and limits of detection were 2.5 and 0.9μgL−1, respectively. The relative standard deviation percent (RSD%) for the extraction and determination at 10 and 100μgL−1 levels of target antioxidants was less than 4.7% (n =7). Finally, the designed method was successfully applied for the preconcentration and determination of the studied SPAs in different fruit juice samples, and satisfactory results were obtained. [Copyright &y& Elsevier]