Preconcentration of Trace Amounts of Zinc in Seawater Using a Dynamically Coated Column of Methyltricaprylylammonium Chloride on Octadecylsilylsilica and Determination by Graphite-Furnace AAS

Abstract

An octadecylsilylsilica (C₁₈) column dynamically coated with methyltricaprylylammonium chloride (C₁₈-Aliquat 336) was examined for the preconcentration of trace amounts of Zn in water samples. Zinc was quantitatively retained on the column from an HCl solution at between 0.5 and 3mol dm^-3, or seawater acidified with HCl, ranging from 0.5 to 1.0mol dm^-3. The retention capacity of the C₁₈-Aliquat 336 for zinc was about 50μmol g^-1 from a 1mol dm^-3 HCl solution. The Zn retained on the column was completely eluted with 3.5ml of 0.1mol dm^-3 nitric acid, and was directly determined by graphite-furnace atomic absorption spectrometry. The precision and accuracy of the present method were demonstrated by analyzing certified reference materials, such as Coastal Seawater (CASS-2) and Riverine Water (SLRS-3). The total procedural blank was 1.9±0.4ng for Zn. The detection limit (3σ of the blanks) was 2.4ng dm^-3 for Zn based on a 125-fold concentration of a 500-ml sample.