Performance Evaluation and Thermodynamic Studies for the Simultaneous Cloud Point Extraction of Erythrosine and Tartrazine Using Mixed Micelles in Food Samples

The present method describes simultaneous determination of erythrosine and tartrazine after cloud point extraction using mixed micelles. The coacervate phase containing the analytes was determined spectrophotometrically by measuring the absorbance at 525 and 425 nm for erythrosine and tartrazine, respectively. Different parameters such as pH, concentration of nonionic (Triton X-100) and cationic surfactant (cetyl trimethyl ammonium bromide (CTAB)), electrolyte concentration, temperature, and incubation time were suitably optimized. Among the various parameters studied, pH and the nature of surfactants played a major role in efficient cloud point extraction of the analytes. A mixture of Triton X-100 and CTAB provided adequate separation efficiency, with enrichment factor of 45.22 and 71.15 for erythrosine and tartrazine, respectively. The method was found to be linear in the concentration range of 0.04-4.00 mu g mL(-1) for erythrosine and 0.05-5.00 mu g mL(-1) for tartrazine. The limit of detection and limit of quantitation obtained were 11.24 and 37.19 mu g L-1 for erythrosine and 13.33 and 44.27 mu g L-1 for tartrazine, respectively. The recovery of these dyes from spiked food samples ranged from 96.5-103.9%. Considering a homogenous monolayer adsorption in the phase separation, Langmuir isotherm model was applied. Thermodynamic parameters such as free energy, enthalpy, and entropy were determined from the plot of solubilization affinity against the reciprocal of temperature. The effect of cations, anions, salts, and some food colorants on the determination of erythrosine and tartrazine was also studied. To demonstrate method applicability, erythrosine and tartrazine were determined in fruit jelly, fruit candy, and fruit syrup samples.