Ion-chromatographic screening method for monitoring arsenate and other anionic pollutants in ground waters of Northern Italy

A novel, rapid ion-chromatographic method for screening anionic pollutants in ground water, based on both conductivity and postcolumn spectrophotometr ic detection, has been developed. A relatively rapid separation of more tha n ten inorganic and polarizable anions was achieved by coupling an high cap acity, hydroxide selective anion-exchange columns (Dionex IonPac AS16) supp lied with an electrolytic eluent generator operating in gradient mode. The good control of the selectivity allowed the determination of polarizable an ions including arsenate, thiocyanate, thiosulfate and perchlorate without i nterference from major components present at levels greater than 100 mg l(- 1). This method was applied to the determination of arsenate in ground wate r samples collected in industrial and agricultural zones of Lombardia (Nort hern Italy). No traces of arsenate were detected in any sample, but added a rsenate cannot be revealed by chromatographic analyses. This fact can be at tributed to different causes, from reduction to the more reduced arsenic fo rm to precipitation or dissolution in organic or inorganic based colloids. Oxidation with hydrogen peroxide seems to be useful for a partial recovery of added arsenate, but a stronger oxidation method, compatible with chromat ographic separation, must be studied. (C) 2001 Elsevier Science B.V. All ri ghts reserved.