Simultaneous microdetermination of chlorine, bromine and phosphorus in organic compounds by ion chromatography

A procedure far the simultaneous microdetermination of chlorine, bromine and phosphorus in organic compounds is described. It consists of ion chromatographic analysis, after suitable dilution, of the solution resulting from the collection in water containing hydrogen peroxide of the combustion products obtained by decomposition of the sample in a Schoniger hash. Before analysis, this solution undergoes a post-combustion procedure involving further hydrolysis of the combustion products which allows a nearly quantitative recovery of phosphorus to be achieved even in the presence of other heteroatoms such as chlorine and bromine. This post-combustion step avoids negative errors in the microdetermination of phosphorus by ion chromatography owing to the minor but not insignificant amounts of both pyrophosphate and a cyclic metaphosphate which are formed together with the predominant orthophosphate in the conventional Schoniger combustion of organophosphorus compounds. The accuracy and precision of the overall procedure were evaluated.