液体阴极辉光放电分析溶液中的痕量铅

Analysis of Trace Pb in Aqueous Solution by Using Liquid Cathode Glow Discharge

以铂针尖为阳极,毛细管穿入石墨碳棒且其顶端溢出的液体为阴极,构建了一种小型化的液体阴极辉光放电发射光谱(LCGD-OES)分析系统,并将其用于溶液中Pb的测定。研究了放电电压、溶液流速、电解质种类、溶液pH等对发射强度的影响,同时用Pb标准物质(GBW(E)080399)和电感耦合等离子体发射光谱(ICP-OES)对LCGD-OES的分析性能进行了评价。结果表明,最优的分析条件为:放电电压650V,pH=1.0的HNO_3为电解质,溶液流速4.5mL/min。Pb的校准曲线线性关系良好,相关系数R^2为0.9913,相对标准偏差(RSD,n=10)为0.5%,检出限为0.380mg/L,功率低于55W。本法对Pb标准物质的测试结果与标准值吻合良好,相对误差为10.0%;对实际水样的测量结果与ICP-OES的测试结果基本一致,样品回收率分别为112.43%和102.81%。以上结果表明,LCGD系统具有稳定性好、灵敏度高、精密度好、准确度高等优点,可以作为一种便携式分析仪器用于水体中Pb的直接检测。

In this paper,a miniaturized liquid cathode glow discharge-optical emission spectrometry(LCGD-OES) was established as a micro-analytical system for the determination of Pb in aqueous solution,in which needle-like Pt acted as anode and the electrolyte overflowing from a quartz capillary served as cathode.The operating parameters such as discharge voltage,supporting electrolyte,solution pH and flow rate were thoroughly investigated.The reference material of GBW(E)080399 and ICP-OES was used for evaluation the analytical performance.The results showed that the optimal conditions were 650 V discharge voltage,pH=1.0HNO3 as supporting electrolyte and 4.5 mL/min as flow rate.The linear relationship of calibration curve was good.The correlation coefficient(R^2),relative standard deviation (RSD),limits of detection (LOD)and energy consumption of Pb were 0.9913,0.5%,0.380 mg/L and 55 W,respectively.Moreover,the determined result of Pb in reference material by LCGD-OES was consistent well with the certified value and the relative error was 10.0%.Good agreement was obtained between the determined results and the reference values obtained with ICP-OES,and the recovery were 112.43% and 102.81%.All results indicated that the LCGD-AES may be developed as a portable analytical instrument for the direct determination of Pb because of its high sensitivity,stability and accuracy,and good precision.