Simultaneous ionic liquid aqueous two-phase extraction and spectrophotometric determination of amaranth and brilliant blue in food samples

Abstract

Aqueous two-phase system (ATPS) consisting of a hydrophilic ionic liquid 1-butyl-3-methylimidazolium bromide and K2HPO4, which is a novel, simple, fast, non-toxic and effective sample pretreatment technique coupled with UV-Vis spectrophotometry, was developed for the simultaneous separation, enrichment and rapid determination of amaranth and brilliant blue. Under the optimal conditions, the extraction efficiency for both analytes was nearly 100% in a one-step extraction. Linear calibration curves were obtained in the range of 25–2400 μg/L for amaranth and 4.5–1300 μg/L for brilliant blue. The limits of detection were 10 and 1.3 ng/mL for amaranth and brilliant blue, respectively. The method was applied to the simultaneous determination of amaranth and brilliant blue in beverages and candy samples. Compared with the results obtained by Chinese national standard method, there was no significant difference after being evaluated by t-test when the confidence level was 95%.