基于衰减全反射-傅里叶变换红外光谱技术的气溶胶中水溶性无机离子定量分析方法研究

A Quantitative Analysis Method of Water-Soluble Inorganic Ions with ATR-FTIR Spectroscopy

利用衰减全反射-傅里叶变换红外(ATR-FTIR)光谱技术探讨了气溶胶颗粒物中SO_4^(2-),NO_3^-,NH_4^+三种水溶性无机离子的快速无损测量方法。利用IC法测量三种无机离子含量的对照值,结合偏最小二乘(PLS)法建立了三种无机离子的定量分析模型,并对模型进行了评价;利用马氏距离判别法对异常值进行了判别与剔除,并探讨了不同光谱预处理方法和不同光谱范围对建模结果的影响,确定了最佳建模参数。结果表明剔除异常值之后经二阶微分处理的模型预测性能较好,SO_4^(2-)在1 220~900cm^(-1)光谱范围内预测性能较好,NO_3^-在1 521~900cm^(-1)光谱范围内预测性能较好,NH_4^+在1 521~1 220cm^(-1)光谱范围内预测性能较好,预测均方根误差分别为1.736 7,1.023 9和1.482 3。所建立的模型为实现对大批量气溶胶样品中三种无机离子的实时快速定量分析建立了基础。

A method of fast nondestructive determination of three kinds of water-soluble inorganic ions including SO4^2-,NO3--,NH4-＋ in aerosol was disscussed.The method of IC measurement values was used on the control of the three kinds of inorganic ion content.The quantitative calibration models of the inorganic ions were developed by using ATR-FTIR spectroscopy combined with PLS algorithm and the model was evaluated.Markov distance discriminant method was used to identify and eliminate outliers,different mathematical treatments for spectra processing and different wavelength ranges were compared to determine the best model and the optimal model parameters was determined.The results showed that second derivative analysis after eliminating outliers can improve the prediction,PLS analysis can get better results for SO4^2-in the range of 1 220-900cm^-1,for NO3-- in the range of 1 521-900cm^-1 and for NH4-＋ in the range of 1 521-1 220cm^-1,the RMSEP were 1.736 7,1.023 9and 1.4823,respectively.The foundation of real-time fast quantitative analysis of the three kinds of inorganic ion in a large number of aerosol samples was established.