Extraction and Determination of Synthetic Food Dyes in an Aqueous Biphasic System Based on Tetrabutylammonium Bromide

Abstract

An aqueous biphasic system (ABS) based on tetrabutylammonium bromide (TBABr) with ammonium sulfate as a salting-out agent was used to extract synthetic food dyes from aqueous solutions. Conditions for the preparation of the TBABr–H2O–(NH4)2SO4 ABS for microextraction preconcentration of Allura Red, Tartrazine, Azorubine, Sunset Yellow, and Fast Green were optimized: tetrabutylammonium bromide, 0.075 M and ammonium sulfate, 33 wt %. The recovery of all of the dyes was no lower than 97% at pH 2.3–9.5 for 1 min. Filtration through nonwoven polypropylene was used to facilitate phase separation and extract isolation. The concentrate was eluted with distilled water, and the dyes in the eluate were determined by spectrophotometry. The limits of detection were 0.02, 0.03, 0.03, 0.04, and 0.02 mg/L for Allura Red, Azorubine, Tartrazine, Sunset Yellow, and Fast Green, respectively. The procedure was applied to determine dyes in drinks, a mouthwash, an Easter kit for dyeing eggs, and the drug Ibuprofen.