State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
School of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
Bull Environ Contam Toxicol. 2021 Aug;107(2):221-227. doi: 10.1007/s00128-021-03258-9. Epub 2021 Jun 15.
At present, the detection of chlorothalonil is generally based on chromatography and immunoassay; both of which are time-consuming and costly. In this study, Surface-enhanced Raman Spectroscopy (SERS) has been successfully utilized in the detection of chlorothalonil coupled with photochemistry and meanwhile, gold nanoparticles were prepared to enhance the Raman signal. Two Raman peaks (2246 cm and 2140 cm) of chlorothalonil were appeared after ultraviolet (UV) irradiation compared to the original solution. Chlorothalonil generated excited and weakened C≡N bonds in its structure by absorbing UV energy, thus leading to two kinds of corresponding peaks. These two kinds of peaks were both selected as analytical peaks in chlorothalonil detection. Different light sources and solvents were made different contributions to the final spectra. Chlorothalonil methanol solution under 302 nm wavelength irradiation was performed the best. The 2246 cm sharp peak represented to the normal C≡N bond appeared at first, which overall trend was significantly increased followed by a gradual decrease. The 2140 cm broad peak represented to the weakened C≡N bond appeared later, which overall trend was increased as the irradiation time passing by and then kept stable. Natural bond orbital (NBO) analysis indicates that the downshift of C≡N bond from 2246 cm to 2140 cm is due to the increase of electronic populations of π* orbital of C≡N bond transited from π orbital excited by UV irradiation. The positively charged C≡N bond had more chance to approach negatively charged gold nanoparticles. The detection limit of chlorothalonil was as low as 0.1 ppm in the standard solution. Orange peels spiked with chlorothalonil oil were also detected in this paper to confirm the practical operability of this method. The SERS method may be further developed as a rapid detection of pesticides that contains a triple bond by utilizing photochemistry.
目前，检测百菌清一般基于色谱法和免疫测定法；这两种方法都既耗时又昂贵。在本研究中，表面增强拉曼光谱（SERS）已成功用于结合光化学的百菌清检测，同时，制备了金纳米粒子来增强拉曼信号。与原始溶液相比，在紫外（UV）辐照后，百菌清出现了两个拉曼峰（2246 cm 和 2140 cm）。百菌清通过吸收 UV 能量使其结构中的激发和减弱的 C≡N 键产生，从而导致两种对应的峰。这两种峰都被选为百菌清检测的分析峰。不同的光源和溶剂对最终光谱有不同的贡献。在 302nm 波长的辐照下，百菌清甲醇溶液的效果最佳。最初出现的尖锐的 2246 cm 峰代表正常的 C≡N 键，整体趋势呈显著增加，随后逐渐减少。较晚出现的 2140 cm 宽峰代表减弱的 C≡N 键，随着辐照时间的流逝，整体趋势呈增加趋势，然后保持稳定。自然键轨道（NBO）分析表明，C≡N 键从 2246 cm 向下移动到 2140 cm 是由于 C≡N 键的π*轨道的电子密度增加，该轨道由 UV 辐照激发的π轨道跃迁而来。带正电荷的 C≡N 键更有可能接近带负电荷的金纳米粒子。在标准溶液中，百菌清的检测限低至 0.1ppm。本文还检测了用百菌清油喷洒的橙皮，以确认该方法的实际可行性。该 SERS 方法可以通过利用光化学进一步发展为快速检测含有三键的农药。
