Evaluation of polypropylene and polyethylene as sorbent packing materials in on-line preconcentration columns for trace Pb(II) and Cd(II) determination by FAAS

Abstract

A novel flow injection solid phase extraction system coupled with flame atomic absorption spectrometer for automatic trace metal determination has been developed. The efficiency of two commercially available low-cost polymers (high-density polyethylene and polypropylene) as packing materials in on-line preconcentration columns for metal extraction was evaluated. Sodium diethyl dithiocarbamate was used as chelating reagent to form the desirable metal complexes while methyl isobutyl ketone was adopted to elute and deliver them into the flame atomizer for measurement and quantification. A comparable study between the two sorbents regarding the analytical performance characteristics was performed and revealed that polypropylene was more suitable than high-density polyethylene regarding the metal complex retention. All main parameters affecting the sensitivity of the proposed method were thoroughly optimized. By adopting polypropylene sorbent and a preconcentration time of 90 s the sampling frequency was 30 h−1, the enhancement factor was 180 and 44, the detection limit (3s) 1.5 and 0.30 μg L−1 while the precision was 2.8% (at 50.0 μg L−1) and 2.9% (at 20.0 μg L−1), for Pb(II) and Cd(II), respectively. The accuracy of the developed method was assessed by the analysis of a certified reference material and spiked environmental water samples.