A new spectrophotometric method for the determination of chlorine-containing organic compounds using 1,5-bis(6-methyl-4-pyrimidyl)carbazone.

Abstract

A new spectrophotometric method for the determination of small amounts of chlorine ion by using 1, 5-bis(6-methyl-4-pyrimidyl)carbazone (MPC) has been established.The proposed method is based on the reduction of the absorbance of silver-MPC complex at 530 nm after the reaction of chlorine ion with the complex to form AgCl in 1 M ethanolic acetic acid solution. Silver-MPC is a violet complex (λmax=530 nm) which is soluble in water, pyridine, dimethylsulfoxide and lower alcohols, and is stable when kept in light-resistant containers. A surfactant was added to the solvent to disperse silver chloride colloid uniformly in the test solution, and this allowed direct measurement of absorbance without the separation of AgCl. The calibration curve conformed to Beer's law between 1×10-5 and 1×10-4 M chlorine ion.This method could be applied to the determination of various chlorine-containing organic compounds listed in The Japanese Pharmacopoeia (JPX), when they were processed by the oxygen flask combustion method described in the General Test Methods of JPX.