SEPARATION AND ANALYSIS OF PRESERVATIVES IN SKINCARE CREAMS BY HIGH TEMPERATURE LIQUID CHROMATOGRAPHY AND SUBCRITICAL WATER CHROMATOGRAPHY

Abstract

Preservatives are chemicals with antimicrobial activity commonly added to foods, pharmaceuticals and cosmetics in order to prolong products' shelf life and to protect the consumer from potential infection. Parabens, the most widely used preservatives worldwide are a family of alkyl esters of para-hydroxybenzoic acid. The most widely marketed para-hydroxybenzoic acid esters are methyl, ethyl, propyl and butyl parabens. Their microbial activity increases as the alkyl chain increases. Parabens are reported to have weak estrogen-like properties. According to Cosmetic Ingredient Review (CIR), limit up to 0.4% (single paraben) or up to 0.8% (mixtures of parabens) can be added to the cosmetic products. Therefore, to monitor the levels of preservatives in cosmetic products is important. High-performance liquid chromatography (HPLC) is the most commonly used separation and analysis technique for the determination of preservative in skincare creams. HPLC involves a consumption of large quantities of organic solvents in the mobile phase. These HPLC organic solvents are toxic, expensive for purchasing as well as their proper disposal. At ambient temperature, water is too polar to serve as a sole chromatographic solvent. Fortunately, at elevated temperatures and under moderate pressures, the polarity of water significantly decreases and liquid water behaves more like an organic solvent. Thus, high-temperature water can mimic organic solvent-water mixtures used in HPLC to achieve liquid chromatographic separation. The goal of this research is to develop high temperature liquid chromatography (HTLC) and subcritical water chromatography (SBWC) methods for the separation and analysis of preservatives in skincare creams to either reduce or completely eliminate the consumption of the harmful organic solvents used in traditional HPLC. A ZirChrom®-DiamondBond-C18 column was used in this study to carry out the separation of preservatives. Preservatives studied include benzyl alcohol, 2-phenoxyethanol, methyl, ethyl, propyl, and butyl paraben. Quantitative analysis of preservatives in three Olay® skincare creams was achieved by HTLC and SBWC. The recoveries obtained by HTLC and SBWC are efficient. The major advantage of HTLC and SBWC techniques is the reduction or elimination of organic solvents used in traditional HPLC.