Separation, enrichment and spectrophotometric determination of erythrosine (E127) in drug, cosmetic and food samples by heat-induced homogeneous liquid–liquid microextraction method

Heat-induced homogeneous liquid-liquid microextraction method (HIH-LLME) has been proposed for separation/enrichment of trace levels of erythrosine in drug, cosmetic and food samples prior to its UV-Vis spectrophotometric determination. Cyclohexylamine was utilised as extraction phase to produce two different phases. It dissolves in water at low temperatures and decreases its solubility in water when heated. Thus, the heated sample forms a two-phase system in NaCl medium and erythrosine was extracted into cyclohexylamine phase. Analytical parameters such as volume of cyclohexylamine, amount of NaCl, pH, effect of matrix ions and temperature have been optimised. Optimum pH has been set at pH 5. The proposed (HIH-LLME) method exhibits a limit of detection (LOD) of 0.006 μg mL⁻¹ and a limit of quantification (LOQ) of 0.021 μg mL⁻¹. A pre-concentration factor was obtained as 37.5 and the relative standard deviation was 2.9%. This method is environmentally sensitive due to the usage of very little organic solvent and at the same time, it is simple and fast and it has a low cost and short extraction period. Cyclohexylamine solvent showed a high affinity and good accessibility for erythrosine.