亚甲基蓝分光光度法测定地表水中硫化物的不确定度研究

Study on Uncertainty in Determination of Sulfide in Surface Water by Methylene Blue Spectrophotometer

硫化物是地表水常规监测的一项重要指标,常用的分析方法有分光光度法、流动注射-分光光度法等。本文分析了采用亚甲基蓝分光光度法测定硫化物过程中不确定度的主要影响因素,包括溶液体积、标准曲线拟合、重复性和分光光度计。结果表明:整个分析过程所带来的相对标准不确定度为0.0218,标准样品205545的不确定度可表示为(3.33±0.07)mg/L。各不确定度分量中校准曲线和重复性测定对结果的影响较大。

Sulfide is an important indicator for routine monitoring of surface water,the commonly used analytical methods include spectrophotometry,flow injection-spectrophotometry,etc.The main factors affecting the uncertainty of testing method for sulfides by methylene blue spectrophotometry were analyzed,including solution volume,standard curve fitting,repeatability and spectrophotometer.The results showed that the relative standard uncertainty of testing method for sulfides was 0.0218,and the uncertainty of standard sample 205545 was(3.33±0.07)mg/L.Among the uncertainty components,the calibration curve and repeatability measurement had great influence on the results.