Poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith microextraction coupled with high performance liquid chromatography for the determination of phthalate esters in cosmetics.

A simple, sensitive, and rapid strategy has been reported in this work which is based on polymer monolith microextraction (PMME) and high performance liquid chromatography (HPLC) for the determination of phthalate esters in cosmetics. A poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-EGDMA) monolithic capillary column is selected as the extraction medium for PMME. In order to obtain optimum extraction efficiency, the conditions of PMME including sample flow rate, sample volume, sample pH, and eluent flow rate have been investigated. Under the optimum conditions, the limits of detection for dimethyl phthalate (DMP), di-n-butyl phthalate (DBP), dicyclohexyl phthalate (DCHP), and di-n-octyl phthalate (DOP) based three times of standard deviations of blank by seven replicated are in the range of 0.7-3.7 ng mL(-1). The reproducibility of the method is obtained with intra-day and inter-day relative standard deviations less than 3.2% and 7.7%, respectively. The method has been successfully applied to the determination of the four phthalate esters in cosmetics with a recovery range of 81.2-108.8% in all the samples.