Use of an Aqueous Methionine Mobile Phase in Identification of Cetylpyridinium Chloride on a Kieselguhr Layer with Preliminary Separation from Nonionic Surfactants

Thin layer chromatography of cationic and nonionic surfactants was performed on kieselguhr ‘G’ layers. Eight amino acids at three different concentration levels were used as aqueous mobile phase systems to examine the chromatographic behavior of cationic and nonionic surfactants. Among mobile phases used, a 0.01% methionine solution was found most suitable for the separation of cetylpyridinium chloride (CPC) from the mixture of nonionic surfactants on kieselguhr layers. The separation is not influenced by the presence of metal cations as impurities in the sample. None of the dyes, except ammonium purpurate and malachite green, hamper the separation. The exposure of the sample to UV radiation (λ = 254 nm) also does not have any adverse effect on the separation of CPC from TritonX-100 and Brij-35. The R _F values of surfactants were found to vary marginally on substitution of l-methionine by its d-isomer in the mobile phase or by the change in pH of the mobile phase (0.01% l-methionine) from 2.9 to 8.8. The proposed method can also be used for preparative thin layer chromatography.

Ali MohammadEmail: