Dispersive solid-phase extraction for determination of fast green and erythrosine dyes in environmental water samples using Zein bio-nanoparticles

Abstract

Colour additives are commonly used in the food industry to improve product appearance and nutritional characteristics. However, effluent containing reactive dyes from food and textile dyeing industries is a substantial cause of pollution in the environment. Simple and ecofriendly trace analysis of two synthetic food azo dyes including fast green (FG) and erythrosine (ER) dyes from environmental water samples was developed by combining dispersive μ-solid-phase extraction with UV-Vis spectrophotometric detection. Zein biopolymeric nanoparticles (ZNPs) were used as a green sorbent for preconcentration of trace amounts of the mentioned food dyes. Based on the anti-solvent method, the ethanolic Zein solution (20 mg) was injected rapidly into the sample, and the ZNPs were produced. After centrifugation, the adsorbed dye was separated, and samples were analysed using a spectrophotometric technique. The impact of various extraction parameters, such as extraction time, adsorbent amount, surfactant type and concentration, ionic strength, pH of sample solution, and desorption conditions, was examined. Under optimised conditions, the linearity ranges were 0.005–1.2 and 0.01–2 µg mL⁻¹ with correlation coefficient (r²) of 0.9970 and 0.9972 for FG and ER respectively. The method has good reproducibility, with relative standard deviations of less than 4.2% (n = 5) and detection limits of 2.5 and 6 ng mL⁻¹ for both dyes respectively. The current approach was used to analyse three environmental water samples (river, canal, and well water), and the dyes recoveries were 94.0–102.6% and 95.7–101.7% for FG and ER respectively. The findings revealed that the proposed approach was convenient, fast, and effective.