Separation and identification of fatty acids in cosmetic formulations containing Brazil nut oil by capillary electrophoresis

Abstract

An analytical method based on capillary electrophoresis (CE) with a partially aqueous electrolyte system was developed to enable the free fatty acids of Brazil nut oil to be identified in cosmetic formulations. In this study, a gel cream formulation was developed and its oil phase was extracted with a mixture of chloroform-methanol-water (1:2:0.8 v/v/v). The chloroform layer was saponified with a methanolic solution of NaOH (0.5 mol L-1) at 75- 80 °C for 25 minutes. Experiments were carried out on a Beckman PACE/MDQ CE system (Fullerton, CA, USA) equipped with an on-column, diode-array detection system set at 254 nm and at 25ºC. The electrolyte consisted of 12.5 mmol L-1 sodium tetraborate buffer pH 7.0, 12.5 mmol L-1 polyoxyethylene 23-lauryl ether, 7.5 mmol L-1 sodium dodecylbenzenesulfonate (used as chromophore for indirect UV detection) and acetonitrile (35% v/v). The proposed method allowed the separation and identification of the fatty acids of Brazil nut oil in a cosmetic gel cream, as well as enabling possible interference by the oily phase components in the formulation to be identified.