Early Warning Analysis of Glyphosate Residues Dynamics on Tea Safety Risk
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Abstract:
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.
