Dimethylglyoxime

The Sylgard 184 and curing agent were purchased from Dow Corning (Midland, MI, USA). Copper(II) sulfate pentahydrate (CuSO₄∙5H₂O, ≥98%), nickel(II) sulfate hexahydrate (NiSO₄∙6H₂O, ≥98%), mercury(II) chloride (HgCl₂, ≥99.5%), and cesium chloride (CsCl, ≥99.999%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The reagents for the detection of each element, namely potassium iodide (KI, ≥99.99%), dimethylglyoxime (DMG, ≥99%), 4,4′-bis(dimethylamino)thiobenzophenone (Michler’s thioketone, MTK, ≥85%), and 4-phenylazo-m-phenylenediamine monohydrochloride (chrysoidine G, CG, ≥95%) were purchased from Sigma-Aldrich.

All chemicals were analytical grade and used as received without further purification. Iron(III) chloride hexahydrate, nickel(II) sulfate hexahydrate, aluminum(III) sulfate hydrate, copper(II) sulfate pentahydrate, phthalic anhydride, dimethylglyoxime (DMG), sodium acetate trihydrate, sodium fluoride, cerium(IV) ammonium nitrate, 1,5-diphenylcarbazide (1,5-DPC), and polydiallyldimethylammonium chloride (PDDA, medium molecular weight) were purchased from Sigma-Aldrich (St Louis, MO, USA). Tris-hydrochloride and ammonium hydroxide were purchased from Mallinckrodt Baker, Inc. (Phillipsburg, NJ, USA). Glacial acetic acid was purchased from Fisher Scientific (Pittsburgh, PA, USA). Nitric acid (18.4M) was purchased from EMD Millipore (Billerica, MA, USA). Milli-Q water from a Millipore deionized water generator (R ≥ 18.2 MΩ cm⁻¹) was used for all experiments. Mixed cellulose ester (MCE) filters were purchased from Fisher Scientific Company (Pittsburgh, PA, USA). Whatman No. 1 qualitative-grade filter paper was purchased from General Electric Company (Schenectady, NY, USA).