草甘膦残留动态对茶叶安全风险的预警分析

采用高效液相色谱-串联质谱法建立了茶树不同部位（根、茎、叶）和土壤草甘膦、氨甲基膦酸的快速检测，其中茶树经超纯水提取，土壤经KOH溶液提取，提取液过C18固相萃取柱净化，然后在硼酸钠缓冲溶液中与9-芴基甲基三氯甲烷（FMOC-Cl）进行衍生反应，其衍生产物在C18色谱柱上以5 mmol/L乙酸铵溶液和乙腈为流动相(含0.1%甲酸)进行梯度洗脱，采用电喷雾离子源、正离子扫描和多反应监测模式检测，同位素内标法定量，系统地研究了提取条件对草甘膦检测影响，结果表明：草甘膦和氨甲基膦酸在2.5~80 ng/mL内线性关系良好，相关系数大于0.999，该方法定量限为0.05 mg/kg。对空白茶树和土壤分别添加0.05、0.40和1.60 mg/kg 3个浓度水平的草甘膦和氨甲基膦酸，平均回收率为76.95%~112.57%，相对标准偏差为2.01%~6.83%（n=4）。该方法快速灵敏稳定，适用于茶树中不同部位和土壤中草甘膦残留的检测。残留动态试验表明：在施药剂量为0.3 g/m2时，草甘膦在叶部的富集量是最大的。随着时间延长，草甘膦在茶树各部位以及土壤中的残留量逐渐降低，且在土壤中的降解速率最快，此研究可为后续草甘膦在非标靶茶树中的吸收、转运和代谢提供技术支持。

Early Warning Analysis of Glyphosate Residues Dynamics on Tea Safety Risk

Rapid detection of glyphosate (GLY) and aminomethyl phosphonic acid (AMPA) in different parts of tea trees (roots, stems, leaves) and soils was established by using high liquid chromatography tandem mass spectrometry. The tea tree was extracted with ultrapure water and the soils was extracted with KOH solution. Then, the extracts were purified by C18 solid phase extraction cartridge, before derivatization with 9-fluorenylmethoxycarbonyl (FMOC-Cl) in a sodium borate buffer. The derivatized sample was separated on an Agilent poroshell C18 column using a gradient elution with the mobile phase composed of 5 mmol/L ammonium acetate and acetonitrile containing 0.1% formic acid. Electrospray ionization in positive ion mode, multiple reaction monitoring, isotopic internal standard method were used to study systematically the effects of extraction conditions on GLY detection. The results showed a good linearity between GLY and aminomethylphosphonic acid in the range of 2.5~80 ng/mL, with the correlation coefficient (r2) higher than 0.999 and the limit of quantification as 0.50 mg/kg. For the blank tea tree and soil samples at three spiked levels (0.05, 0.40, 1.60 mg/kg), the average recoveries of GLY and AMPA were 76.95%~112.57% with the relative standard deviations (RSD) as 2.01%~6.83% (n=4). The established method was rapid, sensitive and stable, thus suitable for the determination of GLY in different parts of tea trees and soils. The dynamic analysis of residual GLY showed that the amount of the GLY accumulated in tea leaves was the highest when the dosage applied was 0.3 g/m2. Over time, the amounts of residual GLY in different parts of tea trees and soils gradually decreased with with the degradation rate of GLY in soil being the highest. This research can provide technical support for the subsequent studies on the uptake, translocation and metabolism of GLY in non-target tea trees.