The Analysis of Plasticizers by Thin Layer Chromatography

The separation of fifty kinds of plasticizers, which are widely used in Japan, was performed by thin layer chromatography, using five kinds of solvent systems and eleven kinds of coloring reagents. The tailing of spots was prevented by addition of small amount of ethyl acetate to the solvent systems. In homologous series, Rf value was increased as the carbon number of alkyl chain increased. The high molecular weight plasticizers, such as epoxidized esters, showed many spots with any of the solvent systems. For detecting the spots of every type of plasticizers, iodine chloroform reagent was effective, and other reagents showed specific coloring for each homologous plasticizers (e.g. resorcinol reagent or thymol reagent for phthalates, 2, 6-dichloroquinone-chloroimide reagent or p-nitroaniline reagent for phosphates and alkaline KMnO4 for maleates). From the results of the experiments, a mixture of unknown plasticizers could be separated and identified from Rf values with five kinds of solvent systems and the coloring reactions by several coloring reagents.