Detection of preservatives in pharmaceutical and cosmetic products using agar gel electrophoresis

A method is described using high voltage agar gel electrophoresis for the separation and microbiological detection of preservatives in pharmaceutical and cosmetic products. The positions of the preservatives were detected as zones of inhibition of a test organism within the nutrient agar gel and can be characterised by their migration, shape and presence of a halo. A wide range of preservatives commonly used in pharmaceutical and cosmetic preparations could be detected in low concentrations. The method however was not suitable for certain volatile preservatives and many primarily antifungal compounds could be detected above their use concentration.