抽风口与烟道间距对AFS-930型原子荧光光度计测定砷、汞的影响

Influence of gap between exhaust fan and flue on determination of As and Hg by atomic fluorescence spectrometery (AFS-930)

为了减少室内有毒氢化物的排放，同时保证测试结果的准确可靠，本文利用原子荧光光度计以As为例在实验的基础上，适当缩短了仪器烟道距上端与抽风机抽风口的距离（h）。该调节对砷测定的影响表现在，h〈10cm时，砷（As）荧光值显著降低，10．00μg／L（As）荧光值由1200左右降低到500～1100，同时，系列标准的浓度-荧光值线性变差，相关系数（r^2）一般〈0．999，特别是其积分曲线不平滑；只有h≥10cm，测试As标准系列时荧光值正常、积分曲线平滑，并且浓度-荧光值相关系数（r^2）〉0．999。将仪器烟道距抽风口的距离h设定为10cm，在这一优化条件下，利用HNO3和HClO4体系（V（HNO3）：V（HClO4）=6：1）中温消解的方法，测试了5个土壤国家标准样品和2个生物国家标准样品中As和Hg量，结果均落在参考值范围内。

Because of the high toxicity of AsH3 gas by-produced in the process of determining As concentration, a ventilator should be used to refresh the air in the room. While the gap （h） between entrance of ventilator and waste gas pipe of instrument might affect significantly the air flow. To select a suitable h, benefit-researcher＇s safety and analysis credibility, we performed a series of experiments on the different h values of 25, 10, 8, 5 and 0 cm. As a result, when h was about 〈 10 cm, the intensities of fluorescence （If） of arsenic （10.00μg/L） standard solution decreased rapidly from about 1200 with h = 25 cm to approximately 500 - 1100, at the same time, the If-Concentration linear corcelation coefficients also fall from 〉 0. 999 to 〈 0.99. Whereas, when h is 25 and 10 cm respectively, the If of arsenic （10.00 μg/L） standard solution is about 1200 and the If-Concentration linearity is generally fine. With h = 10 cm, the determined arsenic and mercury contents of the certified reference materials （GBW - 07401, GBW - 07403, GBW - 07404, GBW - 07407, GBW - 07408, GBW - 07604, GBW - 07601 ） supplied by National Research Center for CRM＇s of China are well consistent with the certified values. Therefore, the recommended h value should be approximately 10 cm for the HG - APS method by APS - 930.