Determination of diethanolamine in cosmetics based on micellar extraction in situ derivatization coupled with high performance liquid chromatography

Abstract

A micellar extraction procedure in situ derivatization method was developed for extraction of diethanolamine in cosmetic samples prior to high performance liquid chromatography analysis. The diethanolamine was taken into a complex with dansyl chloride in an aqueous nonionic surfactant, Triton X-114, medium and concentrated in the surfactant-rich phase. Based on method development, the optimum parameters for the micelle-mediated extraction process were as follows: 4.0% (v/v) of Triton X-114, pH = 9, 1.5 g L⁻¹ solution of derivative reagent, derivatization time of 15 min and derivatization temperature of 50 °C. In addition, the cloud point pre-concentration was optimized under the condition of 15% (m/v) sodium chloride and equilibration at 60 °C for 10 min. The extract obtained was analyzed by high performance liquid chromatography. The micellar extraction in situ derivatization/high performance liquid chromatography method was successfully applied for the determination of trace diethanolamine in cosmetic samples, the limit of detection (LOD) and limit of quantity (LOQ) of diethanolamine were 0.57 μg g⁻¹ and 1.72 μg g⁻¹, respectively. Recovery ranged from 89.9% to 96.4% with obtained relative standard deviations (RSDs) of 3.9% to 5.2%, respectively. The derivatization, extraction and enrichment were completed in the same system. The proposed method was a simple, effective and environmental friendly technique for the analysis of diethanolamine.