Use of the anion-exchange resin amberlite IRA-93 for the separation of arsenite and arsenate in aqueous samples

The method described uses the separation of As(III) and As(V) species in aq ueous samples by means of the anion-exchange resin Amberlite IRA-93. The sa mples were acidified using acetic acid and passed through a glass column fi lled with pre-treated Amberlite IRA-93 resin. As(III) was poorly adsorbed o n the anionic exchanger material, whereas As(V) was retained. The arsenic c oncentration was measured in the column effluent by graphite furnace AAS (G F-AAS). The retained As(V) was eluted from the column using 1 M NaOH. Prior to the determination of the As(V) concentration in the NaOH eluate, the el uate was passed through a glass column filled with a cation-exchange resin (Amberlite 200) to remove sodium ions and minimize the Na+ interference wit h the AAS determination. After calibration the method was applied to the separation of As(III) and A s(V) species in two aqueous extracts of arsenic contaminated soils. The res ults were compared with those obtained from an on-line separation and deter mination of As(III) and As(V) in the aqueous soil extracts using a state of the art HPLC-ICP-MS system.