表面增强拉曼光谱法快速检测茶叶中百草枯与敌百虫农药残留

Rapid detection of paraquat and trichlorfon pesticide residues in tea by surface-enhanced Raman spectroscopy

中文关键词:  茶叶  表面增强拉曼光谱  百草枯  敌百虫  快速检测

英文关键词:tea  surface-enhanced Raman spectroscopy  paraquat  trichlorfon  rapid detection

中文摘要:

      目的 基于花状银衬底的表面增强拉曼光谱(surface-enhanced Raman spectroscopy, SERS)对不同茶类中的敌百虫与百草枯进行定性与定量检测。方法 采用表面增强拉曼光谱技术对不同浓度的百草枯和敌百虫农药标准溶液进行光谱采集和峰位归属, 再对不同茶类茶汤中的梯度农药残留进行检测, 建立峰强与农药残留浓度的线性关系。结果 843 cm?1的拉曼特征峰可作为百草枯的识别峰, 在绿茶、红茶、黑茶茶汤中百草枯的检出限为1.86×10?2 mg/kg, 在乌龙茶茶汤中的检出限为1.86×10?1 mg/kg, 灵敏度均满足国家规定的茶叶中百草枯最大农药残留限量(0.2 mg/kg)对检测方法的要求; 在敌百虫的检测中, 茶汤中咖啡碱的SERS峰强受敌百虫浓度影响, 其峰强随敌百虫浓度的增加而减小且呈现出显著的负线性相关性, 因此可用茶叶中咖啡碱的拉曼特征峰作为敌百虫浓度的间接识别依据, 所建立的回归模型显示, 敌百虫在绿茶、红茶、乌龙茶茶汤中的最低检出限为2.57×10?2 mg/kg; 在黑茶茶汤中的检出限为2.57×10?1 mg/kg, 均可达到国家茶叶中敌百虫最大残留限量(2 mg/kg)对检测方法的要求。结论 使用SERS技术可实现不同茶类茶汤中的百草枯与敌百虫农药残留的简易、准确分析。

英文摘要:

      Objective To detect the trichlorfon and paraquat in different teas qualitatively and quantitatively by surface-nhanced Raman spectroscopy (SERS) based on floral silver substrate. Methods Different concentration of paraquat and trichlorfon pesticide standard solutions were collected spectrum by SERS, and the Raman peaks were all assigned to corresponding group or chemical bond. And then pesticide residues of different gradients in various tea soups were detected and analyzed, and the linear relationship between peak intensity and pesticide residue concentration was established. Results The Raman characteristic peak of paraquat in tea at 843 cm?1 was taken as the distinguishable peak, the limit of detection of paraquat in green tea, black tea, and dark tea soup was 1.86×10?2 mg/kg and the limit of detection of paraquat in oolong tea soup was 1.86×10?1 mg/kg, all the sensitivities met the requirements of the national maximum pesticide residue limit of paraquat (0.2 mg/kg). In the detection of trichlorfon, the SERS peak intensity of caffeine in tea soup was affected by the concentration of trichlorfon, decreased with the increase of the concentration of trichlorfon, and showed a significant negative linear correlation. The regression equations were established by taking the Raman characteristic peaks of caffeine in tea as the basis for indirect identification of trichlorfon concentration. The limit of detection of trichlorfon in green tea, black tea, and oolong tea soup was 2.57×10?2 mg/kg, and the limit of detection of trichlorfon in dark tea soup was 2.57×10?1 mg/kg, all of them could meet the requirements of national maximum residue limit of trichlorfon (2 mg/kg) for tea. Conclusions The pesticide residues of paraquat and trichlorfon in different tea soups can be detected simply and accurately by SESR technology.