百菌清残留检测及其与中药相互作用荧光光谱研究

固定激发波长320 nm，对不同浓度百菌清药液进行荧光光谱实验，发现在352和366 nm处有明显特征峰，随着药液浓度降低，366 nm肩峰逐渐消失，而352 nm特征峰保持稳定;对百菌清浓度和所得发射光谱荧光强度(352 nm)进行指数函数回归分析，相关系数为0.999，实验结果与荧光强度-浓度理论计算公式相符合;对低浓度药液浓度和荧光强度进行线性拟合，其百菌清残留预测模型函数相关系数为0.995，最低检出限为0.018 8 μg·mL-1，定量极限值为0.062 7 μg·mL-1，线性范围为0.062 7～28.45 μg·mL-1。通过对中药材黄芪和枸杞与百菌清混合体系的荧光光谱进行研究，发现两种中药材对百菌清荧光强度都有较强的衰减，表明它们都和百菌清发生了相互作用。经过分析计算，黄芪和枸杞的衰减率分别为88.5%和99.7%，对其建立强度衰减模型函数，相关系数分别为0.994和0.997。研究结果为利用荧光光谱检测百菌清残留提供了实验依据，表明可以采用荧光光谱方法直接对百菌清农药残留进行检测，相关参数值满足检测要求标准，这为进一步利用荧光光谱检测该农药在果蔬中的残留具有重要的参考价值。同时发现药食同源类中药材枸杞和黄芪都能对百菌清荧光特征峰强度产生显著衰减，这为研究利用药食同源类中药材降解农药残留提供了新的研究思路。

Study on Fluorescence Spectra of Chlorothalonil Residues and the Interaction between Chlorothalonil and Chinese Herbal Medicines

The fluorescence spectrum was studied for the chlorothalonil(0.292 8 mg·mL-1) using spectrofluorophotometer. The experiment results showed that the characteristic peaks (352 and 366 nm) are found in the spectrum of chlorothalonil standard solution when the excitation wavelength is 320 nm. And it was found that the shoulder peak gradually disappeared at 366 nm, while the fluorescence peak is stable at 352 nm with the decline of the solution concentration. The exponential functional relationship between the concentration of chlorothalonil and fluorescence intensity at 352 nm was obtained, and its correlation coefficient is 0.999. The experimental results are consistent with the theoretical formula about fluorescence intensity and concentration. The prediction model functions were also obtained through the liner fitting to the chlorothalonil solution of low concentration, and the correlation coefficient is 0.995. The limit of detection (LOD) is 0.018 8 μg·mL-1, the limit of quantification (LOQ) is 0.062 7 μg·mL-1, and the linear range is 0.062 7～28.45 μg·mL-1. And fluorescence spectra were studied for the mixed system of astragalus, medlar and chlorothalonil. It was found that the fluorescence intensity of chlorothalonil solution is all declined with the addition of two kinds of Chinese Herbal Medicines, which indicates that there is an interaction between them. The decay rate of fluorescence intensity was obtained which is 88.5% and 99.7%, respectively. Then the model functions were established between fluorescence intensity and the volume of addition, and the correlation coefficient is 0.994 and 0.997, respectively. This study provides the experimental foundation for the detection of chlorothalonil residues using fluorescence spectrum. It is shown that it is possible to detect pesticide residues of chlorothalonil using fluorescence spectra directly, and the relevant parameter value satisfied the requirement of testing standard. Therefore there is an important value for further detecting the pesticide residues in fruit juice using fluorescence spectrum. It was also found that the fluorescence intensity of chlorothalonil is decreased with the addition of astragalus or medlar, which provides the new research approach to studying the pesticide degradation using medicinal and edible Chinese Herbal Medicines.