Optimization of a field flow pre-concentration system by experimental design for the determination of copper in sea water by flow-injection-atomic absorption spectrometry

摘要

A Plackett-Burman 2~(7X3)/32 design for seven factors (sample pH, sample flow rate, eluent volume, eluent concentration, eluent flow rate, ethanol percentage in the eluent and mini-column diameter) was carried out in order to find the significant vairables affecting the field flow pre-concentration system (FFPS) and the flow injection elution manifold for copper determinaton in seawater samples by flame atomic absorption spectrometry. By using the optimized flow systmes, seawater samples were collected and pre-concentrated in situ by passing them with a peristaltic pump through a mini-column packed with Amberlite XAD-4 impregnated with the complexing agent 4-(2-pyridylazo) resorcinol. Thus, copper si pre-concentrated without the interference of the saline matrix. Once in the laboratory, the mini-columns loaded with copper are incorported into a flow injection system and eluted with a small volume of a 40% (v/v) ethanolic solution of 3 mol l~(-1) hydrochloric acid into the nebulizer-burner systme of a flame atomic absorption spectrometer. Analysis of certified reference mateirals (SLEW-3 and NASS-5) showed good agreement wth the certified value.