Low-density-solvent-based air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection for the determination of synthetic phenolic antioxidants in milk samples

A simple and rapid sample pretreatment technique termed low-density-solvent-based air-assisted liquid-liquid microextraction has been developed for the extraction and preconcentration of three synthetic phenolic antioxidants including butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone from milk samples prior to their analysis by gas chromatography with flame ionization detection. In this method, initially trichloroacetic acid as a proteins precipitation agent is added to the sample, and then it is sonicated and centrifuged. The obtained aqueous phase is removed and the analytes extracted by the proposed method using a low-density organic solvent. Some important parameters such as type and volume of extraction solvent, ionic strength, pH, and centrifugation rate and time were studied. Under the optimum conditions, enrichment factors were obtained in the range of 501-614. LODs and quantification were between 0.76-1.16 and 2.66-3.96 ng mL(-1), respectively. This method is rapid and requires less than 15 min for sample preparation.