Evaluation of Polyvinyl Chloride Functionalized with 3-(2-Thiazolylazo)-2,6- diaminopyridineas a New Chelating Resin for On-line Pre-concentration and Determination of Traces of Cadmium in Real Samples by Flame Atomic Absorption Spectrometry

In the present work, an on-line solid-phase extraction system is proposed for the preconcentration and accurate determination of trace amounts of cadmium(II) ions by flame atomic absorption spectrometry. The preconcentration of cadmium(II) ions was performed using polyvinyl chloride functionalized with 3-(2-thiazolylazo)-2,6-diaminopyridine in a minicolumn system. The adsorbed cadmium(II) ions were then eluted from the sorbent by the eluent. The important influencing parameters such as the sample solution pH, type and concentration of the eluent used for stripping cadmium(II) ions from the sorbent, flow rate of the sample and the eluent, and the amount of adsorbent were investigated in detail. Under the optimum experimental conditions, the linear dynamic range of the method was found to be in the range of 2.0-40.0 μg l-1 (with the determination coefficient equal to 0.9987). The limit of detection and improvement factor were 0.7 μg l-1 and 52.4, respectively. The inter assay precession (RSD%, n = 7) was in the range of 0.8-4.1% at the concentration levels of 5.00, 9.00 and 25.0 μg l-1. The validated method was successfully employed for determination of cadmium(II) ions at trace levels in the spiked water and soil samples with satisfactory results.