[A flow injection on-line unequal flow complexation preconcentration procedure coupled with flame atomic absorption spectrometry for determination of lead in tap water].
A simple, environmentally friendly, cost-effective, and sensitive method was developed for the determination of trace lead in tap water by flow injection (FI) on-line unequal flow complexation preconcentration procedure coupled with flame atomic absorption spectrometry (FAAS). Compared with conventional preconcentration method, the unequal flow complexation preconcentration procedure, increased the flow rate of sample while decreased the flow rate of complexing agent. The new method decreased the dilution effect of sample caused by the chelating agent, increased the sorption preconcentration effect, and increased the enhancement factor. The decrease in the flow rate of chelating agent will not result in a deficient complex formation because the concentration of APDC is much higher than that of the sample's. Compared with other sorption preconcentration methods, such as, multiplexed sorption preconcentration procedure, the unequal flow complexation preconcentration procedure need not to prolong the preconcentration time, but received even better results. Taking lead as a model element, ammonium pyrrolidine dithiocarbamate (APDC) as the chelating agent, and ethanol as the eluent, the proposed FI on-line KR unequal flow complexation preconcentration procedure was coupled with FAAS for the determination of trace lead in tap water. With a sample loading flow rate of 10. 4 mL x min(-1) and preconcentration time of 60 s, the enhancement factor increased from 30 (conventional equal flow complexation preconcentration procedure) to 59 (unequal flow complexation preconcentration procedure), the detection limit (3sigma) of 5.6 microg x g L(-1) was obtained at a sampling frequency of 40 samples x h(-1). The relative standard deviations (n = 11) were found to be 2.1% at the level of 0.5 mg x L(-1). The recovery ranged from 98.5% to 102%. The proposed method has been successfully applied to the determination of lead in tap water samples.
Wang
Zhong-Yuan
ZY
Department of Chemistry, Tongji University, Shanghai 200092, China. zhongyuan764@126.com
Su
Yao-Dong
YD
Li
Shuang
S
Gan
Li-Hua
LH