FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF SULFATE ION WITH A BARIUM CHLORANILATE CELLULOSE REACTION COLUMN

Flow-injection analysis was applied to the determination of sulphate in natural water. The sample plug in the carrier stream (0.5% aqueous ammonium chloride containing 50% ethanol) passes through two columns in series. The first column is packed with cation-exchange resin (ammonium form) to remove interfering cations. The second column is packed with spherical beads of regenerated cellulose containing solid barium chloranilate particles. Sulphate ion in the sample reacts with barium chloranilate in the reaction column to release chloranilate ion, which is eventually monitored by a spectrophotometric detector at 530 nm. This approach is an improvement of a previous technique in which the reaction column was packed with fine barium chloranilate powder. With the use of spherical beads of cellulose containing fine particles of barium chloranilate, the reaction column can be packed more uniformly, giving a more stable baseline and better reproducibility.