The Research Of Determination Of Glyphosate Residues In Wuyi Rock Tea Using High Performance Liquid Chromatography-Tandem Mass Spectrometric Method

Glyphosate (GLY) is a non-selective systemic conductive herbicide, which can effectively control the growth of gramineous broadleaf weeds. It is the most widely used and the largest produced herbicides in the world at the present. Glyphosate, as a type of pesticide with relatively high toxicity, is harmful to human, animal, and ecological environment. With the continuous development of the tea industry, the rapid expansion of the tea plantation area, and the exponentially increased labor cost, glyphosate is exploited as a herbicide in some tea plantations, leading to the presence of glyphosate residues in tea. The detection of glyphosate residue in food has been intensively studied all over the world, however, less efforts have been made for the residue detection in Wuyi rock tea.This thesis was focused on the research of the determination of glyphosate in WuYi rock tea using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After the extraction of tea samples by dichloromethane and water (1:1), the samples were purified by cation exchange method (Bio-Rad CAX), then the derivatization reaction was carried out with 1.0mg/mL FOMC-C1 acetone in borate buffer solution. Acetonitrile with 1% ammonium acetate solution was used as mobile phase. The detection of GLY was accomplished by mass spectrometry with electrospray ionization mode and multiple reaction monitoring mode. It is shown that a linear relationship of GLY was obtained in the concentration range from 1 ng/mL to 10 ng/mL with the correlation coefficients of 0.998. The mean recoveries of blank samples spiked with GLY at 3 concentrations were determined between 78.6% and 94.6%, and the relative standard deviation (RSD) were tested between 5.92% and 7.55%.Meanwhile, to better understand the residual condition of GLY in different planting areas (Zhengyan mountain, Banyan mountain and Zhoucha mountain) and in different varieties of Wuyi rock tea, experiments have been exploited to compare the residual condition of GLY in 10 varieties of Wuyi rock tea (including Shuixian, Rougui, Baijiguan, Tieluohan, Beidou, Queshe, Bantianyao, Jinsuoshi, Shuijingui, Bairuixiang) grown in 10 Zhengyan mountains,10 Banyan mountains and 5 Zhoucha mountains. According to the experiment results, glyphosate residues were not detected in all kinds of Wuyi rock tea in Zhengyan mountains; trace amounts of glyphosate residues were detected in some of Wuyi rock tea in Banyan mountains; a small amount of glyphosate residues were found in the Zhoucha mountains. It is concluded that the current utilization of glyphosate and the amount of glyphosate residues are low in Wuyi rock tea.