The determination of small quantities of metal ions using anthranilic acid

Metal ions which form insoluble anthranilates may, if present singly, be determined by dissolving the anthranilate in acid and titrating the liberated anthianilic acid with perchloratocerate. Or preferably the anthranilic acid may be determined absorptiometrically with N-(1-naphthyl) ethylenediamine hydrochloride after diazotisation. Under the conditions described quantities of the order of 1–5 micromoles of metal are conveniently determined by the volumetric method and one fifth of such amounts by absorptiometry. With the latter the use of larger Spekker cells would increase the sensitivity of the method.By making use of the insolubility of its complex in acetate buffers copper may be determined in the presence of other metals if these are not in excessive amounts. Various other determinations. are also possible.Attempts to use the fluorescence of the liberated anthranilic acid have indicated the method to be less satisfactory than absorptiometry.