A novel ion pair based surfactant assisted microextraction modified by orthogonal signal correction partial least squares for determination of food dyes

Abstract

Simultaneous preconcentration and spectrophotometric determination of two common synthetic food dyes, Sunset yellow and Quinoline yellow by ion pair based surfactant assisted microextraction (IP-SAME) and chemometric methods were developed in this study. The application of cationic surfactant, zephiramine as ion pairing and disperser agent simultaneously was proposed. The effective factors on the extraction efficiency like type and volume of extraction solvent, type and volume of surfactant, pH, extraction time and ionic strength of the sample were optimized. In this method, a mixture of 120 µL of zephiramine (as emulsifier agent) and 25 µL of carbon tetrachloride (as extraction solvent) were rapidly injected by a syringe into 10.0 mL sample solution (pH 6.0) which formed a cloudy solution. After centrifugation, the sediment phase was analyzed using UV–vis spectrophotometry. Under the optimum conditions, the calibration graphs were linear in the range of 2.0–60.0 ng mL−1 with detection limits of 0.71 and 0.68 ng mL−1 for Sunset yellow and Quinoline yellow, respectively. A very high preconcentration factor of 714 with micro-volume of extraction solvent was obtained. Repeatability and reproducibility of 1.17 and 2.35 for Sunset yellow, 1.94 and 2.67 for Quinoline yellow were achieved. Sunset yellow and Quinoline yellow demonstrated a strong spectra overlap with traditional spectrophotometry technique. Partial least squares multivariate calibration method was applied to resolve overlapped UV–vis absorption spectra of mixtures of dyes and orthogonal signal correction was employed as a preprocessing method. The root mean square error of prediction for Sunset yellow and Quinoline yellow with and without orthogonal signal correction was 0.56, 1.62 and 0.80, 1.70, respectively. The simple, practical, and environmentally friendly proposed method was successfully used for the simultaneous determination of synthetic colorants in various food samples (jelly powder, fruity candy, smarties and pastille) and soft-drinks with recoveries of 94.5–104.6%.