A Simple and Highly-available Microextraction of Benzoic and Sorbic Acids in Beverages and Soy Sauce Samples for High Performance Liquid Chromatography with Ultraviolet Detection

A simple and highly-available air-assisted dispersive liquid-liquid microextraction procedure with organic phase solidification (AA-DLLME-OPS) was developed as new approach for pretreatment of complex sample matrix. Menthol was investigated as novel extractant for the AA-DLLME-OPS. In this procedure, a cloudy solution of fine molten menthol droplets is formed when a mixture of molten menthol and aqueous sample is rapidly aspirated into a dispenser and injected into an extraction vial. In the AA-DLLME-OPS, air bubbles promote molten menthol dispersion into aqueous sample phase. Finally, the obtained mixture is cooled and menthol phase is solidified because of the low melting point, which facilitates collection for analysis. To demonstrate the efficiency of the suggested approach, the AA-DLLME-OPS procedure was applied for the HPLC-UV determination of benzoic and sorbic acids as proof-of-concept analytes in beverages and soy sauce samples. The procedure developed provides microextraction of benzoic and sorbic acids from samples with recovery from 93 to 105% and from 96 to 101%, respectively. Under optimal experimental conditions the linear detection ranges were found to be 0.1-150 mg L for benzoic acid and 0.05-100 mg L for sorbic acid with LODs calculated from a blank test, based on 3σ, 0.03 mg L and 0.02 mg L, respectively.