On-line supported liquid membrane enrichment-flow injection-spectrophotometric determination of trace lead (II) in water

An on line supported liquid membrane enrichment flow-injection spectrophotometric method for the determination of trace lead (II) in water has been developed, and a flow carrier, dithizone dissolved in kerosene was used in the supported liquid membrane extraction system. Experiment conditions were optimized. The optimum conditions are as follows:. pH value of sample is 6, the concentration of re-extraction citric acid is 0.5 mol/L, the concentration of carrier dithizone is 0.03%, the aperture of polytetrafluoroethylene membrane is 0.3 mu m, the enrichment time is 30 min. Under optimum conditions, the detection limit for lead (II) is 0.2 mu g/L, the linear range of the determination is 0.5-100 mu g/L. The method can be applied to enrichment and determination of trace lead (II) in tap water, river water and waste water with satisfactory results.