Flow-Injection Spectrophotometric Determination of Micro Amounts of Sulfate Ion in Surface- and Sea-Water Samples with a Barium Chromate Reaction Column

摘要

A rapid and simple flow-injection method using a reaction column packed with barium chromate powder is described for the determination of micro amounts of sulfate ion in surface- and sea-water samples. An aqueous solution containing 4.5mM sodium acetate and 4% ethanol was used as a carrier solution at a flow rate of 0.8ml/min. The absorbance of the chromate ion (which corresponds to the sulfate ion concentration) in the carrier solution from the reaction column was measured using a photometric detector at 370nm. Interference from some cations was eliminated by the use of a cation-exchange resin column installed in front of the reaction column; interference from some anions was reduced by using the carrier solution mentioned above. The concentration range from 0.5 to 5ppm of the sulfate ion in practical water samples can be determined by the proposed method with good reproducibility.