Separation and determination of acesulfame-K in soy sauce by capillary electrophoresis with contactless conductivity detection using liquid-liquid extraction and field-amplified sample injection

Abstract

A new method was established for the sensitive determination of artificial synthetic sweetener acesulfame-K in soy sauce by capillary electrophoresis (CE) with field-amplified sample injection (FASI)and capacitively coupled contactless conductivity detection (C4D). Liquid-liquid extraction (LLE) technology was employed to eliminate the complex matrix interference co-existing in soy sauce. Ethyl acetate was used as the extraction solution. The pH of the sample solution was adjusted to 1.7, and both inorganic salts and organic compounds causing interferences were effectively removed by LLE. The type and volume of the extraction solvents, pH of the sample solutions, extraction method and extraction time were investigated in detail. Under the optimized experimental conditions, acesulfame-K in soy sauce was well separated and sensitively detected. The limit of detection and limit of quantification were 0.15 mg/kg and 0.48 mg/kg, respectively. The accuracy was tested by spiking acesulfame-K into soy sauce samples, and the recoveries ranged from 92.3% to 108.1%. The relative standard deviations were below 8.0%. The proposed method can meet the requirements for the fast screening and sensitive detection of acesulfame-K in soy sauce samples.