Sodium arsenate dibasic heptahydrate na2haso4 7h20

PS and LDPE resin pellets (3 mm in particle size) purchased from Sigma-Aldrich Australia were used as the adsorbents. Multi-element standard solution 4 for ICP (40 mg/L of As) was supplied by Sigma-Aldrich Pty Ltd., Australia. The solution was diluted by deionized water with a resistivity of 18 MΩ. Analytical grade sodium arsenate dibasic heptahydrate (Na₂HAsO₄⋅7H₂0) and sodium arsenite (NaAsO₂), purchased from Sigma-Aldrich Pty Ltd, were dissolved with deionized water to obtain As(III) and As(V) stock solutions (100 mg/L). The phosphoric acid (H₃PO₄, 85% w/w) and hydroxylamine hydrochloride (NH₂OH⋅HCl, 99% purity) were also obtained from Sigma-Aldrich Pty Ltd. Then, solutions of 1.0 M phosphoric acid and 0.2 M hydroxylamine hydrochloride were prepared by diluting their original standard solution with deionized water. All plasticware and glassware were soaked in 2% (v/v) HNO₃, followed by repeated rinsing with deionized water, and then dried before use.

Cefoperazone (cefoperazone sodium salt) was purchased from Chem-Impex International Inc. (Wood Dale, IL) and stored with desiccant at 4 °C. iAs^V was ACS grade (≥98% pure) sodium arsenate dibasic heptahydrate (Na₂HAsO₄·7H₂0, Sigma-Aldrich, St. Louis, MO). All chemicals were used as received with no additional purity analysis.