Solid-Phase Extractor with Ram Horn Powder for Lead and Cadmium Determination in Environmental Samples by Flame Atomic Absorption Spectrometry

Sitki Baytak*

Department of Chemistry, Faculty of Science and Arts, Harran University, 63100, S¸ anliurfa, Turkey,
Tel.: +90 414 344 00 20-1283;
Fax: +90 414 344 00 52;
E-mail address: sbaytak@harran.edu.tr

Abstract
In the present paper, a separation/preconcentration procedure is presented for the solid phase extraction of Pb and Cd from environmental samples on a natural adsorbent (ram horn powder, RHP), prior to their determination by flame atomic absorption spectrometry (FAAS). The procedure is based on the adsorption of the bivalent ions of these metals as their 1-nitroso-2-naphthol-3,6-disulphonic acid chelate on the mini column packed with (RHP) followed by elution with 10 mL 1 M HCl and determination by flame atomic absorption spectrometry (FAAS). The influences of pH, amounts of chelating agent, eluent type, flow rate and sample volume were optimized and the analytical figures of merit were determined. Considering analytical figures of merits for the two elements, in the order of Pb and Cd recoveries of 97 ± 2% and 100 ± 2%, limit of detection of 5.62 ng mL^–1 and 1.74 ng mL^–1 (with enrichment factor of 50), sorbent capacity of 4.55 mg g^–1 and 2.69 mg g^–1 (0.022 mmol g^–1 and 0.024 mmol g^–1) were found, respectively. The enrichments were made at concentration 0.02 to 0.2 µg mL^–1 of the two metals from 500 mL original water samples, at pH 4–8. Diverse ions of Mn(II), Co(II), Fe(III), Zn(II), Ni(II), Mg(II) and Cu(II) up to 10 µg L^–1 level, did not interfere with Pb and Cd. The accuracy of the method was checked by using standard reference materials (tea leaves GBW-07605 and fish tissue IAEA-407). Results demonstrated good agreement with the certified values. This procedure was applied for the determination of Pb and Cd in various waters, tap water, Ataturk Dam water and thermal water samples and in carrot and lettuce samples (recoveries >95%, relative standard deviations <8%).

Keywords: Lead, cadmium, preconcentration, ram horn, solid-phase extraction, atomic absorption spectrometry.