不等流速络合法流动注射预富集火焰原子吸收测定自来水中的铅

A Flow Injection On-Line Unequal Flow Complexation Preconcentration Procedure Coupled with Flame Atomic Absorption Spectrometry for Determination of Lead in Tap Water

建立了一种环保、高效、简便的不等流速络合法流动注射与火焰原子吸收联用测定自来水中痕量铅的新方法。通过调节样品溶液和络合剂的流速,即增大样品溶液流速,减小络合剂(吡咯啶二硫代氨基甲酸铵:APDC)流速,从而增大了浓集系数,提高了富集效率,和传统等量络合法相比,富集倍数大大提高。样品进样流速10.4 mL.min-1,进样时间60 s,Pb的浓集系数由传统方法的30达到59,检测限为5.6μg.L-1,样品输出为40.h-1。0.5 mg.L-1Pb2+的相对标准偏差(n=11)为2.1%。Pb2+在自来水中的回收率范围为98.5%到102%。此法用于自来水中痕量Pb的测定,获得了满意的结果。

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·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（3σ） of 5.6μg·L-1 was obtained at a sampling frequency of 40 samples·h-1.The relative standard deviations （n=11） were found to be 2.1% at the level of 0.5 mg·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.