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On-line preconcentration of vapor forming elements on resistively heated w-coil prior to their determination by atomiz absorption spectrometry

Cankur, Oktay
Vapor generation in atomic spectrometry is a well established technique for the determination of elements that can be volatilized by chemical reactions. In-situ trapping in graphite furnaces is nowadays one of the most popular methods to increase the sensitivity. In this study, resistively heated W-coil was used as an online trap for preconcentration and revolatilization of volatile species of Bi, Cd and Pb. The collected analyte species were revolatilized rapidly and sent to a quartz Ttube atomizer for AAS measurement. Although the nature of revolatilized species of Bi and Pb are not clear, they are probably molecular since they can be transported at least 45 cm without any significant decrease in the peak height values. However, cadmium is revolatilized from the trap surface as atoms. The experimental parameters were optimized for the highest vapor generation, trapping and revolatilization efficiencies. The concentration limits of detection calculated by the 3 of blank solution were found to be 0.0027, 0.0040 and 0.015 ng/mL for Bi (18 mL), Cd (4.2 mL) and Pb (2 mL), respectively; enhancement factors in the sensitivity were 130, 31 and 20, respectively. These values are comparable with those obtained by in-situ trapping in graphite furnaces or even ICP-MS found in the literature or better. Sensitivity can be improved further for Bi and Cd using larger sample volumes, but purification of blank is required for Pb. Certified standard reference materials were analyzed for the assessment of accuracy of developed method.