光谱检测水体中磷酸三钠浓度的实验研究

Experimental Study on Determination of Trisodium Phosphate Concentration in Water Based on Spectral Technique

以不同浓度的磷酸三钠溶液为研究对象,探究紫外/可见吸收光谱用于检测水体中磷酸三钠溶液浓度的可行性。使用不同光源和不同光程组合的3套吸光度测量装置采集不同浓度下磷酸三钠样液的光谱数据,进而分别对三组实验数据采用不同预处理方法进行预处理,偏最小二乘(PLS)模型结果表明三次实验均采用Savitzky-Golay(S-G)卷积平滑预处理方法效果最好;接着采用蒙特卡洛交叉验证(MCCV)算法对校正集中奇异样本进行剔除,对剔除奇异样本后的全波段数据建立PLS模型,模型结果表明MCCV法有助于提高PLS模型的预测性能;最后采用相关系数法三种实验选取的主要特征波长分别为214.0998,218.8371和204.66 nm,为了建立一个精度较高且具有普适性的模型,依据以上三个主要特征波长选取磷酸三钠的特征波段为200~222 nm,并建立相应特征波段PLS模型,结果表明该模型可用于磷酸三钠溶液浓度的定量分析和预测。所以采用光谱技术快速检测水体中磷酸三钠溶液浓度具有一定的可行性,该研究为开发快速检测水体中无机磷浓度的仪器设备提供一定的理论基础。

In this paper,different concentrations of trisodium phosphate solutions were used as research objects to explore the feasibility of UV/visible absorption spectra for detecting the concentration of trisodium phosphate solution in water.Three sets of absorbance measuring devices with different light sources and different optical path combinations were used to collect the spectral data of trisodium phosphate sample solution at different concentrations,and then the three groups of experimental data were pretreated by different pretreatment methods,the results of partial least squares(PLS)model showed that the best pretreatment method was Savitzky-Golay(S-G)convolution smoothing;then the method of Monte-Carlo cross validation(MCCV)was used to eliminate the singular samples in the calibration set,and the PLS model was established for the whole band data after the singular samples were removed,the results showed that MCCV method could improve the prediction performance of PLS models;finally,the main characteristic wavelengths of trisodium phosphate in three experiments were selected by correlation coefficient method,which were 214.0998,218.8371 and 204.66 nm respectively,in order to establish a highly accurate and universal model for trisodium phosphate,the characteristic band of trisodium phosphate was selected from 200 to 222 nm based on the above three main characteristic wavelengths,and the corresponding characteristic band PLS models were established,the results showed that the model could be used quantitative analysis and prediction of trisodium phosphate concentration solution.Therefore,itis feasible to use hyperspectral technology to detect concentration of trisodium phosphate in water rapidly,and this study provides a theoretical basis for the development of instruments and equipment for the rapid detection of inorganic phosphorus concentration in water.