Simultaneous preconcentration of lead and cadmium ions with methyltrioctylammonium chloride supported on microcrystalline naphthalene and determination by flame atomic absorption spectrometry

Abstract

A sensitive and selective preconcentration method has been developed for the determination of trace amounts of lead and cadmium ions by using naphthalene-methyltrioctylammonium chloride as an adsorbent. Lead and cadmium ions were retained by the adsorbent in the minicolumn as PbI₄^2- and CdI₄^2-, respectively. The column was washed by 5 mL of 2 mol L^-1 nitric acid solution to elute the adsorbed cations. The collected eluents then were determined by flame atomic absorption spectrometry (FAAS). Potential factors affecting on the recovery of the analytes were investigated. Meanwhile optimum conditions were established. The preconcentration factor for lead (II) and cadmium (II) have been 300 and 100, respectively. The calibration curves were linear in the range of 3 to 100 ng mL^-1 for Pb²⁺ and in the range of 1 to 100 ng mL^-1 for Cd²⁺, in the original water samples. The detection limits for Pb²⁺ and Cd²⁺ are 0.42 and 0.072 ng mL^-1 respectively. On the other hand, the relative standard deviation (RSD) for 11 replicate measurements of 20 ng mL^-1 Pb²⁺ and Cd²⁺ were 2.2% and 1.4% in the initial solution respectively (n=11). The developed method was successfully applied for the determination of trace Pb²⁺ and Cd²⁺ ions in a variety of water samples.