Switchable fatty acid based CO2-effervescence ameliorated emulsification microextraction prior to high performance liquid chromatography for efficient analyses of toxic azo dyes in foodstuffs.

An in-situ chemical reaction based dispersive procedure termed as CO2-effervescence assisted emulsification microextraction was first utilized for pre-concentration of Sudan dyes in spices. It is simple, quick, and efficient; based on a switchable fatty acid (hexanoic acid, pKa ∼ 4.8). The extraction agent is able to be switched into hydrophobic/hydrophilic forms in pH-changeable media, leading to facile and effective dispersion and phase's separation. The method was proved by the analysis of spiked samples. Optimization was statistically performed, resulted in maximum extraction efficiencies. Under optimal conditions, method validation was assayed in the aqueous solutions. Wide linearity with high R2 values and low detection limits (1-5 ng mL-1) were obtainable. Also, enrichment factors were 62-66 with proper repeatability (%RSDs < 6.8, n = 3). Good validations in terms of recovery (86.6-104.5%) and repeatability (%RSDs < 7.8, n = 3, C = 15 and 30 µg g-1) in foodstuffs confirmed a great effectiveness of the method in complex matrices.