ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Ultra-trace determination of Pb(II) and Cd(II) in drinking water and alcoholic beverages using homogeneous liquid-liquid extraction followed by flame atomic absorption spectrometry

Samat Kinaree and Saksit Chanthai

Department of Chemistry and Centre of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen, 40002, Thailand

E-mail: sakcha2@kku.ac.th

Abstract: The determination of Pb(II) and Cd(II) in different sample matrices, including drinking water, distilled spirits and fruit wine, was carried out by flame atomic absorption spectrometry (FAAS) after pre-concentration using homogeneous liquid-liquid extraction (HLLE). First, the HLLE method was optimised with lead diethyldithiocarbamate (Pb-DDTC) complex which was extracted with a perfluorooctanoate anion (PFOA⁻) dissolved in lithium hydroxide under acidic conditions. The optimum extraction conditions, using 0.01 M DDTC, 0.05 M PFOA⁻, 3 M HCl and 1 mL of 30 vol. % acetone, were obtained. The Pb-DDTC complex in the nitric acid digest of the samples (50–150 mL) was extracted quantitatively into a drop of 100 μL of sediment phase. The sediment phase dissolved in 1 vol. % HNO₃ with at least 3–5 mL of the final volume was then determined by FAAS, affording a pre-concentration factor of 10–50. Hence, the HLLE method afforded an increase in both sensitivity and selectivity for the metal determination by conventional FAAS, resulting in ultra-trace level detection of Pb(II) in all samples analysed (drinking water, 9.2–23 ng mL⁻¹; distilled spirits, 23–50 ng mL⁻¹; fruit wine, 24–53 ng mL⁻¹). In addition, the proposed method could successfully be applied to Cd(II) determination in these samples.

Keywords: pre-concentration – lead – cadmium – drinking water – distilled spirits – wine

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0459-9

Chemical Papers 68 (3) 342–351 (2014)