Arsenic-sulfides confound anion exchange resin speciation of aqueous arsenic

• Published in: Water research (Oxford) Vol. 38; no. 5; pp. 1155 - 1158
• Main Authors: Jay, Jenny Ayla, Keon Blute, Nicole, Hemond, Harold F., Durant, John L.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-03-2004; Elsevier Science
• Subjects: Adsorption; Analysis methods; Anion Exchange Resins - chemistry; Applied sciences; Arsenic - chemistry; Arsenic - isolation & purification; Exact sciences and technology; Hydrogen-Ion Concentration; Interference; Ion exchange; Natural water pollution; Pollution; Speciation; Sulfides - chemistry; Thioarsenites; Water - chemistry; Water analysis; Water Purification - methods; Water treatment and pollution; Thioarsenites; Adsorption; Ion exchange; Water analysis; Speciation; Interference; Chemical analysis; Arsenates; Anionic resin; Arsenites; Arsenic V; Accuracy; Analysis method; Water quality; Arsenic III; Water pollution; Quantitative analysis
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2003.11.014

A field-portable anion exchange resin method (often cited as the Ficklin method (1983)) has been extensively used to distinguish between dissolved arsenite (As(III)) and arsenate (As(V)) species in natural waters. As(III) occurs largely as As(OH)
3, which is uncharged at ca. pH 7, while As(V) is negatively charged and will sorb to the resin. However, we show that negatively charged As(III)-sulfide (thioarsenite) species, important at sulfide concentrations >10
μM, also bind to the anion exchange resins, and therefore might be interpreted incorrectly as As(V). Furthermore, we show that nitrogen-purging, which results in a conversion of As(III)-sulfides to arsenite, can be used to obtain accurate arsenic speciation when resins are used on sulfidic water samples.