Ultramicro determination of chlorine in organic compounds with sealed tube dry combustion

Abstract

A new method for ultramicrodetermination of chlorine in organic compounds using a sealed tube dry combustion has been developed. A sample below 1 mg was weighed and placed at the bottom of a Pyrex glass tube (i.d.: 6 mm, l: 18 cm, one end closed) using a platinum scoop and a long-handled forceps. An oxygen stream was gently introduced into the tube using a thin metal pipe and the tube was sealed off at the position of 5～6 cm from the open end remaining a sharp tip end. Several sealed tubes thus prepared were heated in a cylindrical electric furnace at 580 °C for 1 h and the samples were decomposed completely. After cooling, every tube was held vertically with the tip end down and pressed to the bottom of a small beaker containing absorption liquid (60% 2-propanol). The absorption liquid entered through the broken end so that the chlorine species in gas phase were absorbed during 30 min standing. The inside wall of the combustion tube was then washed by a thin jet stream from a metal capillary tube and the liquid was titrated potentiometrically with 0.001 M silver nitrate solution. Statistic evaluation of the analytical data for several standard materials yielded standard deviations of approximately 0.2%. © 1989, The Japan Society for Analytical Chemistry. All rights reserved.