A nephelometric method for the determination of sulphate in the presence of barium by using chloroaminobiphenyl: application to organic compounds and hydrocarbon oils

Abstract

The method described for the determination of sulphate in the presence of barium can also be extended to the determination of sulphur in organic compounds and hydrocarbon oils containing barium. After oxygen-flask combustion of the sample, ammoniacal EDTA can be added directly to the solution and the total sulphate then determined nephelometrically after precipitation with 4-chloro-4′-aminobiphenyl. Alternatively, free sulphate can be determined separately by direct precipitation as chloroaminobiphenyl sulphate after filtering off precipitated barium sulphate; the latter can then be dissolved in ammoniacal EDTA solution and the sulphate also determined as chloroaminobiphenyl sulphate.