针对紫外分光光度法（UV法）检测混有干扰物质的硝酸盐氮溶液浓度精度不高的问题，提出一种基于主成分分析（principal component analysis，PCA）和BP神经网络的硝酸盐氮浓度检测方法。通过微型光谱仪物质成分检测系统测得硝酸盐氮试剂在196 nm～631 nm波段的吸光度数据，分为测试集和训练集。通过PCA计算训练集，得到主成分。根据BP算法搭建三层人工神经网络。将所得主成分除以8后输入网络展开训练。训练过程中采用留一法交叉验证。用该模型计算训练集和测试集，所得值与真实浓度的平均相对误差分别为2.411 5%和1.553%。实验结果表明，该方法能较好检测出混有干扰物质的硝酸盐氮溶液浓度。

Aiming at the problem of inaccurate detection of the nitrate nitrogen solution concentration with interfering substances in ultraviolet spectrophotometry (UV method), a nitrate nitrogen concentration detection method based on principal component analysis (PCA) and BP neural network was proposed. First, the absorbance of the nitrate nitrogen reagent at 196 nm~631 nm was measured by the material composition detection system of the micro-spectrometer, which was divided into test set and training set. Then, the PCA was used to calculate the training set to obtain the principal components. Finally, a three-layer artificial neural network was built based on the BP algorithm. The obtained principal components were divided by 8 and input into the network for training. During the training, the leaving-one method was adopted for cross-validation. This model was used to calculate the training set and test set, the mean relative error between the obtained results and the true concentration is 2.411 5% and 1.553% respectively. The experimental results show that the method can better detect the concentration of the nitrate nitrogen reagent with interfering substances.