Abstract: Application of barium chromate spectrophotometry in determination of total sulfur content in by-product gas mixture of chloroacetic acid production was studied.Critical problems,such as gas collection,sample solution treatment,and barium chromate suspension preparation were discussed.Sulfur in various compounds in gas mixture was totally converted to sulfate radical by oxidizing with H₂O₂ after absorption by alkaline agent.Obtained sulfate radical would react with barium chromate suspension,proportionally displacing chromate.Solution absorbance was thus proportional to the concentration of sulfate radical.The absorbance was found to be at 372 nm by this method.The method had a good linearity at 0~10 mg/L sulfate radical.Precision and accuracy of the easy operating method meet the test requirements in practical application.

Key words: chloroacetic acid, sulfur, barium chromate, spectrophotometry