Determination of cationic surfactants as the preservatives in an oral solution and a cosmetic product by capillary electrophoresis.

摘要

In this study, a capillary electrophoresis method was developed for the determination of cationic surfactants, benzethonium and cetylpyridinium ions, which are commonly used as preservatives in various pharmaceutical and cosmetic products. Determination was performed in a fused-silica capillary using a mixed 75mmol/L phosphoric acid and 50% acetonitrile electrolyte at pH 2.5. Analysis of benzethonium and cetylpyridinium ions was achieved in around 5min. Repeatability in migration times (R.S.D.%) for benzethonium and cetylpyridinium ions were 0.3. The calibration curves were linear from 0.0125 to 0.400mmol/L for benzethonium ions and from 0.025 to 0.400mmol/L for cetylpyridinium ions. The minimum detection limits (signal-to-noise ratio=3) are 1.47 and 4.30mug/mL for benzethonium and cetylpyridinium ions, respectively. The method was applied to the analysis of benzethonium ion in a cosmetic product and cetylpyridinium ion in a mouthwash.