Selective collection of selenium(IV) on anion-exchange resin with azothiopyrine disulphonic acid

Azothiopyrine disulphonic acid (ATPS) has been shown to be terfunctional, namely it can form a selenotrisulphide by reaction of its thiol group with selenium(IV), bind to an anion-exchange resin by ion-exchange through its sulphonate group, and be strongly physically adsorbed on the ion-exchange resin, ATPS adsorbed on the resin does not bleed into solution even in the presence of sodium chloride and hydrochloric acid. The collection of seleniurn(IV) is practically complete when ATPS is added to a selenium(IV) solution and the reaction product is collected on the anion-exchange resin. Selenium(IV) is not satisfactorily collected, however, by reaction with anion-exchange resin loaded with ATPS. The sorbed selenium can be eluted [as Se(IV)] with 13M nitric acid and directly determined fluorometrically in the eluate.