Indirect spectrophotometric method for the microdetermination of chlorine or bromine in organic compounds using 1,5-diphenyl carbazide

A spectrophotometric method for the microdetermination of chlorine or bromine in organic compounds is described. The method is based on an oxygen-flask combustion yielding chloride or bromide, which is then reacted with an excess of solid silver chromate. The combined precipitates of unreacted silver chromate and chloride or bromide are collected and the free chromate (equivalent to the chloride or bromide originally present) is determined spectrophotometrically using 1,5-diphenylcarbazide at λmax.= 540 nm. The method was applied satisfactorily to a wide range of chlorine-and bromine-containing organic compounds with an average absolute error of ±0.14% and a coefficient of variation (seven determinations) of better than 1.1%.