流动注射在线预富集测定环境样品中痕量铅

Determination of Trace Lead in Water Samples by Flow Injection On-Line Filterless Precipitation-Dissolution Preconcentration

流动注射在线无过滤沉淀-溶解系统被应用于火焰原子吸收测定环境水样中痕量铅。通过样品溶液和氨溶液的混合已经可以达到痕量铅的在线析出。结果沉淀物无需过滤就被收集在编结反应器的内壁上。引入1mol/L的HNO3溶液来溶解沉淀物并将分析物输送至火焰原子吸收光谱仪(FAAS)进行在线分析。样品载入流速为3.5mol?L-1/m in,富集时间40 s,增强因子37,检测频率60/h。检测限(3σ)为7.5μg/L。50μg/L水平时,精密度(RSD,n=11)为2.9%。采用该方法测定用简单水溶液标准校准后的国家标准材料(GBW 08607,河道水),所得铅浓度0.96±0.04g/g。结果与标准值(1.00±0.02g/g)非常接近。该方法也可以成功应用于多种水样中痕量铅的测定。

A flow injection on - line filterless precipitation - dissolution system is developed for the FAAS determination of trace lead in water samples. On - line precipitation of trace lead is achieved by merging the sample solution with an ammonia solution. The resultant precipitates are collected onto the inner walls of the knotted reactor without filtration. A flow of I mol/L HNO3 is introduced to dissolve the precipitates and to deliver the analyte for the on -line FAAS detection. With a sample loading flow rate of 3.5mL . L-1/min for a 40 - second preconcentration, an enhancement factor of 37 with a sampling frequency of 60/h is obtained and the detection limit （3） is found to be 7.5ug/L. The precision （RSD,n = 11 ） is 2.9% at the 50ug/L level. With the proposed method, the concentration of lead in a certified reference material （GBW 08607, River Water） is determined to be 0.96 0.04 ug/g using simple aqueous standards for calibration. These results are in good agreement with the certified value （1.00 ±0.02ug/g）. The method is also successfully applied to the determination of the trace lead in a variety of real water .samples.