基准波长法测定溶液温度的研究

近红外光谱分析已广泛应用于工业、农业等领域，然而其测量精度极易收到外界干扰因素的影响，其中温度变化最不易控制，且是一个不可忽视的影响因素。文章基于溶液中溶质与溶剂的置换效应，提出了一种对样品进行温度测量的基准波长法，并以葡萄糖水溶液作为研究对象，对该方法进行了理论推导和实验研究。溶液中溶质浓度和温度均发生变化时，基准波长1 525 nm处的吸光度变化量完全受温度变化的影响，而与溶质浓度无关，因此根据基准波长点处的吸光度变化可以获得样品温度信息。计算不同温度下纯水光谱与30 ℃下纯水光谱之间的吸光度变化量，获得基准波长点处吸光度变化值与温度的一元线性回归模型，以此为基础对溶液进行了温度计算。实验结果表明，该方法能对样品的温度进行准确测量，获得的温度误差为0.03 ℃。

Study on Temperature Measurement of Solution by Reference-Wavelength Method

Near-infrared (NIR) spectroscopy has been widely used in agriculture, medicine, petrochemical and food industries. However, the measurement precision of NIR spectroscopy is adversely affected by the change in external conditions. Among these influence factors, temperature fluctuation is harder to be controlled than other conditions such as contact pressure and measurement position. Based on the displacement effect between solvent and solute molecules in solution, a reference-wavelength method for temperature measurement of solution is presented in the present paper. The theoretical expression of the method was introduced. The experiment was designed to measure the spectra of glucose aqueous solution under different temperatures, and the effect of eliminating the temperature disturbance was evaluated. When the temperature and solute concentration of solution change simultaneously, the absorbency difference value at reference-wavelength is insensitive＇ to solute concentration, and is totally affected by temperature fluctuation. Therefore, according to the absorbanee difference, the actual temperature of the sample can be calculated. The regression model of temperature measurement was.established, and the solution temperature was calculated based on this model. The information about temperature can be acquired exactly by reference-wavelength method, and the experimental results showed that the average error of calculated temperature is 0. 03 ℃.