Modified microdetermination of sulfate ion: Its application to flask combustion for organic sulfur

Abstract

An accurate titration method has been introduced for the determination of sulfate ion in connection with the microdetermination of organic sulfur using the flask combustion. Arsenazo(III) has shown superior reproducibility to that of thorin or sulfonazo(III) as it was used as an indicator during the titration with barium perchlorate solution in a nonaqueous medium. A further improvement of the reproducibility has been attained by a back titration of excess barium perchlorate with standard sulfuric acid solution. Application to the flask combustion of organic sulfur has been successfully achieved with an excellent accuracy of a standard deviation of ±0.04% from a series of analytical data. Simultaneous determination of halogens and sulfur has been also accepted with the method.