QUANTITATIVE-ANALYSIS OF QUATERNARY AMMONIUM ANTISEPTICS USING THIN-LAYER DENSITOMETRY

A thin-layer chromatography method for quantitative analysis of quater nary ammonium antiseptics is described. Silanized silica gel was used as the stationary phase, The mobile phase consisted of methanol-25% (m /v) sodium acetate solution-acetone (65:35:20). The method is able to separate the chain homologues of benzalkonium chloride, cetylpyridiniu m chloride and cetrimide. Detection was performed using a colour react ion with potassium triiodide solution. The different homologues were q uantified using UV densitometry at 400 nm. A number of commercial samp les was analysed using this method. From the results it appears that i t is worthwhile to have a limit test for the composition of quaternary ammonium antiseptics in pharmacopoeial monographs, the more so as the antibacterial activity depends on it.