PM2.5中典型水溶性离子在线观测标准曲线优化研究

为了研究在线离子色谱法测定大气PM2.5中NH4^+、NO3^-、SO4^2-的不确定性来源,探讨了标准曲线的浓度范围及浓度梯度设置对离子浓度结果的影响,并对标准曲线设定方案进行了优化。结果表明:不同浓度范围的标准曲线对于NH4+的浓度结果有较大的影响,存在1. 87%~14. 91%的偏差,对于NO3^-、SO4^2-的影响较小,相对偏差分别为2. 94%和2. 82%;非均匀布点和均匀布点标准曲线定量NH4+的结果存在4. 15%~4. 25%的偏差,对于NO3^-和SO4^2-,相对偏差分别为0. 10%和5. 99%。对于二次拟合的NH4^+,在样品浓度波动较大时,可以将样品划分为低浓度范围和高浓度范围,分别选用低浓度段标准曲线和高浓度段标准曲线,以期得到更合理的浓度结果。

Optimization of Online Observation Standard Curves of Typical Water-Soluble Ions in PM2.5

To research the uncertainty of online measurement of ammonium,nitrate and sulfate in PM2.5 by ion chromatography,two sets of contrast experiments were set to explore the impact of calibration range and layout method of standard curves on the concentration results. Standard curves of different concentration ranges showed a great influence on the quantitative result of NH4^+ with a deviation of 1. 87%-14. 91%,which had a small influence on NO3^- and SO4^2- with a relative deviation of 2. 94% and 2. 82%,respectively. Standard curves of non-uniform distribution and uniform distribution had a deviation of 4. 15%-4. 25%,0. 10% and 5. 99% for NH4^+,NO3^- and SO4^2-,respectively. When the concentration of NH4^+ fluctuated greatly,the samples could be divided into a low concentration range and a high concentration range,and the low concentration section standard curve as well as the high concentration section standard curve were respectively selected to obtain more reasonable results.