Electrolyte-assisted microemulsion breaking in vortex-agitated solidified floating organic drop microextraction for preconcentration and analysis of Sudan dyes in chili products

Abstract

For the extraction and determination of trace amounts of Sudan I–IV dyes in chili product samples, a simple and efficient liquid phase microextraction technique was developed using electrolyte-assisted microemulsion breaking in vortex-agitated solidified floating organic drop microextraction (VA-SFODME-EAMB) and high performance liquid chromatography. Under optimal conditions, 5.0 mL of sample solution yielded a pre-concentration factor of 62. Linearity (0.5–2500 ng mL⁻¹, R² > 0.99), the limit of detection (0.16–0.24 ng mL⁻¹), and the limit of quantification (0.53–0.80 ng mL⁻¹) were used to validate this method. The precision, expressed as relative standard deviation (% RSD), was calculated using seven and five experiments with mixed Sudan dyes at a concentration of 500 ng mL⁻¹. Intra- and inter-day analyses validated the % RSD precision data (<3.5 and 7.0%, respectively). For the analyzed real samples, the recoveries of these dyes ranged between 90.1% and 109%. This newly proposed method is simple, rapid, and environmentally friendly without using both a disperser solvent and a centrifugation step to separate the aqueous and organic phases. In particular, it is applicable for food analysis as a useful screening test of illegal adulteration with Sudan dyes.