消除浊度影响是直接光谱法检测水质COD的关键技术问题。 此源于紫外-可见光谱法检测水质参数的关键依赖于化学计量法所建立的准确的水质参数分析模型, 而浊度是影响其建模的一个重要参数。 为此, 选取福尔马肼浊度液和邻苯二甲酸氢钾标准溶液, 开展了紫外-可见吸收光谱法检测水质COD的浊度影响实验研究, 获得了选定溶液在245, 300, 360和560 nm几个特征波长点的吸光度随浊度变化的最小二乘法拟合曲线, 分析了吸光度随浊度的变化规律。 研究结果表明, 在240～380 nm的紫外光谱段, 由于引起浊度的颗粒物对有机物产生了吸附, 致使浊度对水样的紫外光谱影响较为复杂; 在380～780 nm的可见光谱区域, 浊度对光谱的影响则是随着波长的增大而减弱。 基于此, 开展了多元散射校正法对受浊度影响的水样光谱进行校正试验。 对某溪水水样的紫外-可见吸收光谱进行多元散射校正, 通过处理前后光谱对比表明, 浊度引起各个波长点的基线偏移都得到了有效的校正, 而在紫外区域特征并未减弱。 接着对选取的三种液体的紫外-可见吸收光谱进行多元散射校正, 实验结果表明: 该方法可在不影响水样紫外-可见吸收光谱特征的前提下对其吸收曲线进行有效的校正, 这不仅提高了光谱法检测水质COD的信噪比, 而且还为化学计量法建立准确、 有效的水质检测COD分析模型进行数据预处理提供了一种新途径。

Eliminating turbidity is a direct effect spectroscopy detection of COD key technical problems. This stems from the UV-visible spectroscopy detected key quality parameters depend on an accurate and effective analysis of water quality parameters analytical model, and turbidity is an important parameter that affects the modeling. In this paper, we selected formazine turbidity solution and standard solution of potassium hydrogen phthalate to study the turbidity affect of UV - visible absorption spectroscopy detection of COD, at the characteristics wavelength of 245, 300, 360 and 560 nm wavelength point several characteristics with the turbidity change in absorbance method of least squares curve fitting, thus analyzes the variation of absorbance with turbidity. The results show, In the ultraviolet range of 240 to 380 nm, as the turbidity caused by particle produces compounds to the organics, it is relatively complicated to test the turbidity affections on the water Ultraviolet spectra; in the visible region of 380 to 780 nm, the turbidity of the spectrum weakens with wavelength increases. Based on this, this paper we study the multiplicative scatter correction method affected by the turbidity of the water sample spectra calibration test, this method can correct water samples spectral affected by turbidity. After treatment, by comparing the spectra before, the results showed that the turbidity caused by wavelength baseline shift points have been effectively corrected, and features in the ultraviolet region has not diminished. Then we make multiplicative scatter correction for the three selected UV liquid-visible absorption spectroscopy, experimental results shows that on the premise of saving the characteristic of the Ultraviolet-Visible absorption spectrum of water samples, which not only improve the quality of COD spectroscopy detection SNR, but also for providing an efficient data conditioning regimen for establishing an accurate of the chemical measurement methods.