随着现代农业的迅速发展, 使用农药的种类和数量也在逐步增加, 随之带来的农药残留问题引起了人们的广泛关注。 敌百虫是一种有机磷杀虫剂, 用于农业防治多种害虫及牲畜体内外寄生虫。 人体摄入过量的敌百虫会引发人体免疫功能的问题, 甚至危及生命。 因此, 对敌百虫的残留检测至关重要。 太赫兹波由于具有透视性、 安全性和高光谱分辨能力的特点, 近年来得到了较快的发展和应用, 成为一种新的检测技术, 并被应用于**、 工业、 半导体、 通信、 生物医学、 制药、 农产品及食品等多个领域。 与传统的检测方法相比, 太赫兹光谱技术具有操作方便、 耗时短、 成本低以及无损的特点。 将太赫兹频域光谱用于土壤中敌百虫的检测。 对敌百虫纯品压片的光谱进行分析, 结果发现敌百虫在1.18, 1.55和1.91 THz处存在特征吸收峰。 通过密度泛函理论的B3LYP/6-31G(d)基组对敌百虫单分子进行计算, 结果发现敌百虫在1.59和1.94 THz存在两个振动模式, 解释了敌百虫特征吸收峰的来源, 验证了实验结果的准确性。 此外, 采集了土壤中不同含量(0.5%, 1%, 5%, 10%, 20%, 30%, 40%和50%)敌百虫压片的24条光谱, 实验发现: 当浓度大于5%时, 随着含量的升高, 混合样品的吸光度也随之增加, 呈现良好的线性关系。 将24条光谱以3∶1比例划分为校正集和预测集, 并借助偏最小二乘法对光谱进行建模。 模型具有相对较高的相关系数(＞0.993 04), 较低的校正均方根误差(＜0.021 9)、 预测均方根误差(＜0.024 6)和交叉验证均方根误差(＜0.028 6)。 研究表明: 太赫兹频域光谱能够用于定性检测土壤基质中的敌百虫, 并且太赫兹频域光谱结合化学计量学方法可以对土壤中的敌百虫含量进行预测。 该研究为土壤基质中农药残留的定性与定量分析提供了一种新方法, 同时为土壤中的污染物检测提供了新的思路。

With the rapid development of modern agriculture, the use of pesticides has been increasing in both kind and level, and the corresponding problems of pesticide residue have attracted wide attention. Trichlorfon is an organophosphate insecticide used to control a variety of pests and parasites in livestock in the agriculture. Excessive intake of trichlorfon in the human body can cause problems in immune function, and even life-threatening. Therefore, the detection of trichlorfon residues is very important. Due to the unique properties of perspectivity, safety and spectroscopic fingerprinting ability, THz waves have achieved significant advances and applications as a new detection technology, and have beenin the fields of defense, industry, semiconductor, communication, biological medicine, pharmaceutical, agroproducts, food etc. Compared with traditional pesticide detection methods, terahertz spectroscopy has the characteristics of easy operation, short time-consuming, low cost and non-destructive. In this paper, terahertz frequency domain spectroscopy (THz-FDS) is used to detect trichlorfon in soil. The spectrum of pure trilobite tablets was analyzed. It was found that trichlorfon had characteristic absorption peaks at 1.18, 1.55 and 1.91 THz. DFT model B3LYP and basis function 6-31G(d) were used to calculate the single isolated molecule of trichlorfon to explain the source of these absorption peaks and verify the accuracy of the experimental results. In addition, 24 spectra of different contents (0.5%, 1%, 5%, 10%, 20%, 30%, 40%, and 50%) of trichlorfon in the soil were collected. It was found that the absorbance increased with the increase of the content when the content is more than 5%, showing a good linear relationship. The 24 spectra were divided into a calibration set and a prediction with a ratio of 3∶1, and were modeled by partial least squares method. The model has a relatively high correlation coefficient (>0.993 04), lower corrected root means square error (<0.021 9), a predicted root mean square error (<0.024 6), and a cross-validation root mean square error (<0.028 6). This paper provides a new method for the qualitative and quantitative analysis of pesticide residues in soil, as well as a new idea for the detection of pollutants in soil.