Coulometric investigation of the drying methods for the standard reference materials potassium dichromate and sodium carbonate.

The water content of dried potassium dichromate and sodium carbonate, which had been heated at various temperatures and then cooled in a "desiccated" atmosphere of argon, was measured by a coulometric microdetermination method. The amounts of water in the dried standard reference materials depended mainly on the heating temperature and only a little on the desiccant used. The dichromate and carbonate contained less than 50 ppm of water when they were heated at temperatures higher than 200 degrees and 250 degrees respectively and then cooled in an atmosphere of argon desiccated with magnesium perchlorate. Sulphuric acid was not advisable as the desiccant for sodium carbonate.