Determination of Sulfate Ion by the Cation Exchange Resin

Studies on the Automatic Analysis of Salt Manufacturing Samples (Part 3)

Abstract

In order to determine automatically sulfate ion of salt manufacturing samples, Technicon's autoanalyzer with the cation exchange resin (Bio-Rex 70) was investigated.
In this method, the sample solution was first passed through a cation exchange column, in orderthat cations such as alkaline earth group wereto be removed from the sample.Next, the sulfateion in effluent was reacted with alcoholic solution of MTB-Ba complex, and then it was eliminatedas a fine Barium sulfate crystal.
Finally, quantity of sulfate ion was fixed indirectly by absorbancy measurement of gray color at 460nm, in which intensity of this gray color is quantitatively proportioned to the sulfate ion presentedunder the alkaline condition.
In this method, the relation between the absorbancy of the solution and the sulfate ion concentrationwas curvilinear to 100mg/l.
This method has the same accuracy as the conventional Barium chromate method, and can analyze continuously 15-20 samples per hour.