High-performance liquid chromatography determination of antioxidants in cosmetics after cloud point extraction using dodecylpolyoxyethylene ether

Abstract

A new and efficient cloud-point extraction (CPE) method for the determination of antioxidants including propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in cosmetics has been established combining with high-performance liquid chromatography (HPLC). The non-ionic surfactant dodecylpolyoxyethylene ether (AEO₉) was chosen as an extraction solvent due to its low cloud-point temperature and short phase separation time and it is well-known as an environmentally friendly solvent. Factors affecting CPE (volume of the extraction solvent, sample pH, extraction time, and equilibration temperature) were optimized. Under the optimised conditions, detection limits in the range from 1.4 to 8.5 ng mL⁻¹ were obtained. Linearity is over a wide range from 1 to 1000 μg mL⁻¹ with a relative standard deviation under 4.8%. The high recoveries of the spiked cosmetics were obtained in the range of 90–110%. It was successfully utilized to determine the amounts of antioxidants in real cosmetics without the need for tedious pretreatments.