基于并非所有化学物质都具有良好的拉曼信号这一事实,本文重点研究了含氰基农药的拉曼沉默区信号。在甲醇-水(1:1,v/v)为溶剂的优化条件下,在302nm光源照射20分钟,并使用0.5mol/L的KI作为聚集剂,通过2230cm-1的拉曼沉默区信号建立了用于唑酯酯的表面增强拉曼光谱(SERS)检测方法,并通过检测不同浓度唑酯酯的加标葡萄来验证。对于啶虫脒,在2180cm-1、2205cm-1、2125cm-1和2130cm-1的峰值也可以鉴定出其他四种带有氰基的农药,辛硫磷,噻虫啉和半胱氨酸,分别。当唑菌酯或啶虫脒分别与不含氰基的毒死蜱混合时,它们在毒死蜱拉曼沉默区域的SERS信号没有受到干扰,同时与不同比例(1:4,1:1和4:1)的倍羟氨苄混合,分别,每两种含氰基的农药可以通过拉曼沉默区域的变化来区分。进一步,将四种有或没有氰基的农药以1:1:1:1的比例混合在一起(啶虫脒,Cymoxanil,氮菌酯毒死蜱),即使在0.5毫克/升的浓度下,每种农药仍然可以被鉴定出来。结果表明,SERS方法结合紫外线照射可以提供一种新的方法来监测拉曼无声区域中具有C=N性能的农药,而不受食品基质的干扰。
Based on the fact that not all chemical substances possess good Raman signals, this article focuses on the Raman silent region signals of pesticides with cyano group. Under the optimized conditions of methanol-water (1:1, v/v) as the solvent, irradiation at 302 nm light source for 20 min, and the use of 0.5 mol/L KI as the aggregating agent, Surface-enhanced Raman spectroscopy (SERS) method for
azoxystrobin detection was developed by the Raman silent region signal of 2230 cm-1, and verified by detecting the spiked grapes with different concentrations of
azoxystrobin. Other four pesticides with cyano group also could be identified at the peak of 2180 cm-1, 2205 cm-1, 2125 cm-1, and 2130 cm-1 for acetamiprid, phoxim, thiacloprid and cymoxanil, respectively. When
azoxystrobin or acetamiprid was mixed respectively with chlorpyrifos without cyano group, their SERS signals in the Raman silent region of chlorpyrifos were not interfered, while mixed with cymoxanil in different ratios (1:4, 1:1 and 4:1), respectively, each two pesticides with cyano group could be distinguished by the changes in the Raman silent region. In further, four pesticides with or without cyano group were mixed together in 1:1:1:1 (acetamiprid, cymoxanil,
azoxystrobin chlorpyrifos), and each pesticide still could be identified even at 0.5 mg/L. The results showed that the SERS method combined with UV irradiation may provide a new way to monitor the pesticides with C≡N performance in the Raman silent region without interference from the food matrix.