A rapid method for the estimation of impurities in saccharin and sodium saccharin

Abstract

A procedure is described for the detection and estimation of o-toluenesulphonamide, saccharin-o-toluenesulphonylimide, toluene-2,4-disulphonamide, saccharin-Csulphonamide, o-sulphamoylbenzoic acid, p-sulphamoylbenzoic acid and benzoic acid in saccharin and sodium saccharin using thin-layer chromatography on Kieselgel GF,,,. The solvent system used is chloroform-methanol-strong ammonia solution (100: 50: 11.5). Compounds containing a free sulphonamide group are detected by an "N-chloro" reaction, while the other compounds are detected by examining the chromatograni in ultraviolet light (253.7 mp). Impurities in commercial saccharin and sodium saccharin are estimated by comparison on the chromatogram with standards containing purified saccharin or sodium saccharin and suitable amounts of the impurities. F the impurities likely to be present in saccharin (I), p-sulphamoyl-0 benzoic acid (p-acid, 11) has received the most attention ; the method As most saccharin is manufactured by oxidising o-toluenesulphonamide (o-amide,