茶叶中甲萘威农残表面增强拉曼光谱(SERS)结合快速前处理检测方法的建立

采用表面增强拉曼光谱(SERS)技术结合快速前处理方法,分析绿茶中甲萘威农药残留,对比纳米竹炭(NBC)和N-丙基乙二胺(PSA)填料及用量去除茶叶基质效应的效果。结果表明,PSA对茶叶基质的净化效果较差,而NBC净化效果明显,其最优用量为30 mg。以金溶胶为增强基底,结合密度泛函理论,得到定性定量分析茶叶中甲萘威农药残留的3个特征谱峰:1103、1213、1557 cm^-1。以1557 cm^-1的峰强度,建立茶叶中甲萘威农药残留线性分析方程,该方程在0.28～5.56 mg/kg范围内,线性关系良好,决定系数R^2为0.9744,方法回收率在76.5%～94.9%之间,相对标准偏差(RSD)在3.87%～6.98%之间。该方法分析茶叶中甲萘威农药残留的最低检出浓度可达到0.83 mg/kg,符合国家规定标准1 mg/kg,单个样本检测时间在10 min内完成。研究表明,采用SERS技术结合快速前处理方法分析茶叶中农药残留是可行的。

Establishment of Detection Method of Carbaryl Residues in Green Tea by SERS and Rapid Pretreatment

Surface-enhanced Raman spectroscopy( SERS) combined with rapid pretreatment method was used to rapidly analyze carbaryl pesticide residues in green tea.Nano bamboo charcoal( NBC) and primary secondary amine( PSA) were used to eliminate the matrix effects of green tea extracts.The results showed that PSA had poor purification effect,but NBC had obvious purification effect and the purification was optimal when the dosage of NBC was 30 mg. Gold nanoparticle was used for SERS measurement.In combination with density functional theory,three characteristic peaks of carbaryl in green tea such as 1103,1213,1557 cm^-1 were found.A linear equation for the determination of carbaryl pesticide residues in tea was established based on the peak strength of 1557 cm^-1.The equation had a good linear relationship in the range of 0.28~5.56 mg/kg,and R2 was0.9744. The recovery rates of the method were 76.5%~94.9%,and the relative standard deviations( RSD) were 3.87%~6.98%.And the minimum detectable concentration of carbaryl pesticide residues in green tea was 0.83 mg/kg by the method,which was in line with the national standard( 1 mg/kg). And SERE detection could be performed within 10 min. The results demonstrated that SERS combined with rapid pretreatment method was feasible for detecting pesticide residue in tea.