大气中痕量气态硒系列的蜂窝状、环形扩散管采集与分析

Collection and Analysis of Trace Gaseous Selenium Species in Atmosphere with Honeycomb and Annular Denuders

建立了一种新型的用于检测大气中气态硒的分析系统 ,即蜂窝状扩散管 (HD)采集 微分脉冲阴极溶出伏安法 (DPCSV)系统。研究表明 :2 %HNO3 2 %甘油对气态硒的收集效率为 99 1%和环形扩散管 (AD)相比 ,HD的收集效率和收集容量都更大。硒浓度升至 4 0 μg L时分析校准曲线仍然呈良好的线性。 5ng硒的RSD(n =5 )为 1 2 6 % ,检出限 (3σ)与测定限分别是 0 .96ng m3和 3.19ng m3。测定三个硒标准的平均回收率为98 8%。与国家标准分子荧光法比较 ,相对误差小于± 8.3%。测得的实验室大气中气态硒系列总量为 3.2～4 .4ng m3。本分析系统准确灵敏、重现性好、操作简单、可适用于户外现场操作 ,经试验还可用于大气中其它气态金属 (或准金属 )元素系列的采集与分析 。

A new analytical system has been developed for the determination of total gaseous selenium content in the atmosphere by honeycomb denuder collection followed by measurement with differential pulse cathodic stripping voltammetry (DPCSV). The collection efficiency of 2% HNO3/2% glycerine mixed solution coated in honeycomb denuder for gaseous selenium was 99.1% at the flow rate of 1 L/min for 3 h. Compared to annular denuder, the collection efficiency and capacity of honeycomb denuder were higher than annular denuder at the same flow rate of 1 L/min for the sampling time of 3 h. Excellent linearity was maintained up to Se concentration of 40 mug/L. A precision of 1.3% RSD (n=5) for 5 ng Se was obtained the limit of detection (3sigma) and the limit of quantitative determination were estimated to be 0.96 ng/m(3) and 3.19 ng/m(3), respectively. The total content of gaseous selenium in the atmosphere of our laboratories was 3.2similar to4.4 ng/m(3). The relative deviation was <&PLUSMN;8.3% when compared with the conventional molecular fluorescence analytical (MFA) method. The average recovery of selenium in the three selenium standards using our analytical system reached 99%. The analytical system is accurate, sensitive, simple, it can be used for in situ analysis, and will have a broad prospects.