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 was 0.9744.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.