SERS结合快速前处理检测绿茶中毒死蜱农药残留

doi:10.3964/j.issn.1000-0593(2020)02-0550-06

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Abstract Tea is one of the main economic-crops in China. During tea planting, the unreasonable use and abuse of pesticides lead to serious pesticide residues in tea. At present, the classical chemical laboratory methods are adopted to detect the pesticide residues in tea, but there are some shortcomings such as complex pretreatment, time-consumption and high cost in the laboratory methods. Therefore, it is urgent to study the rapid detection method of pesticide residues in tea to supervise the quality and safety of tea market. In this study, Nano Bamboo Charcoal (NBC) purifier was used to reduce the matrix-induced enhancement of tea substrate. Surface-enhanced Raman spectroscopy (SERS) was employed to detect Chlorpyrifos residues in green tea, and a rapid detection method for analyzing Chlorpyrifos residues in green tea was developed. Different doses of NBC (0, 15, 20, 25, 30 mg) were used to remove the matrix effects. The optimal dosage of NBC was obtained by comparing the purification effect and SERS of different NBC dosage. The recovery experiment was carried to verify the reliability of the optimized pretreatment method. The results showed that NBC had obvious purification effect and the green tea substrates such as pigment and so on matrix-induced enhancement were reducing when the dosage of NBC was 20 mg. It was proved that this optimized pretreatment method was suitable for decreasing the matrix-induced enhancement of tea substrate by recovery tests. Density functional theory was used to simulate the theory Raman spectrum of chlorpyrifos. The theoretical and experimental Raman spectrums of chlorpyrifos were compared and spectral peaks of their functional groups were assigned. Five characteristic peaks of Chlorpyrifos in green tea such as 526, 560, 674, 760 and 1 096 cm^-1 were found. Within the scope of the concentration of 0.28~11.11 mg·kg^-1, a line relation was developed between the peak intensity of 1 096 cm^-1 and the concentration of Chlorpyrifos of tea extract, y=0.017 5x+0.909 2 and R² was 0.986 2, indicating a good linear relationship. The average recovery rates of the method were 96.71%~105.24%, and the relative standard deviations (RSD) were between 2.36%~3.65%. The minimum detection concentration of Chlorpyrifos residues detected by this method was about 0.56 mg·kg^-1 and the detection time of a single sample was performed within 15 minutes. The result demonstrated that SERS combined with rapid pretreatment method was feasible for rapidly detecting pesticide residue in tea.

Key words：SERS; NBC; Chlorpyrifos; Pesticide residues; Rapid pretreatment

Received: 2018-12-17 Accepted: 2019-04-26

ZTFLH:

O657.3

Corresponding Authors: WU Rui-mei E-mail: wuruimei036@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)02-0550-06 OR https://www.gpxygpfx.com/EN/Y2020/V40/I02/550