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To investigate the effect of glyphosate stress on the growth and shikimic acid metabolism of tea (Camellia sinensis L.) plants, tea seedlings were cultured in nutrient solution with different concentrations of glyphosate and the visual phytotoxicity on tea leaves was observed. The non-targeted analysis of non-volatile metabolites in the leaves and quantitative determination of shikimic acid and glyphosate in the leaves were carried out by ultra-high performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometry. The results show that the tea seedlings under the high dose of glyphosate (200 mg⋅L-1) treatment exhibited characteristics of pesticide damage, while the tea seedlings under the low dose of glyphosate (50 mg⋅L-1) treatment and control did not show apparent pesticide damage. Mass spectrometric and statistical analysis indicates that there were significant changes in the contents of shikimic acid pathway metabolites in the leaves of glyphosate-treated tea seedlings, with shikimic acid being one of the main differential metabolites. Within 21 d, the accumulation of shikimic acid in leaves was highly positively correlated with the absorption amount and action time of glyphosate. When the absorption amount of glyphosate was larger than 28 mg⋅kg-1, the shikimic acid metabolism in tea plants was significantly inhibited, resulting in a large accumulation of shikimic acid in tea leaves. Compared with the control group, the content of shikimic acid in tea leaves affected by pesticides increased about 16-fold. This study shows that shikimic acid is one of the main metabolites of tea plants in response to glyphosate stress. [ABSTRACT FROM AUTHOR]

A multi-residue method for the determination of 88 pesticides in tea using gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. The target compounds were extracted with acetonitrile by accelerated solvent extraction (ASE), and the extracts were cleaned up by solid phase extraction (SPE) with a Carbon/NH2 cartridge and eluted with acetonitrile-toluene (3:1, v/v) before the identification and quantification of the residues by GC-MS/MS. Performance characteristics, such as accuracy, precision, linear range, limits of detection (LODs) and limits of quantification (LOQs), for each pesticide were determined. At low concentration level spiked (6.4 microg/kg), the average recoveries were in the range of 70%-100% for 87.5% analytes and the relative standard deviations (RSDs) were lower than 15% for 87.5% analytes. The quantification of analytes was carried out using the most sensitive transition for every compound and by matrix-matched standards calibration. The LOQs (S/N = 10) were less than 10 microg/kg for 86.4% analytes. The method is sensitive, accurate, reliable and suitable for the simultaneous determination of multi-residue pesticides in green tea, Woolong tea, black tea and Puer tea.