Development Of The Analytical Platform For Multiresidual Pesticides In Traditional Chinese Medicine By GC-MS

Medicine safety is very important for general public health. The adverse events caused by the pesticide residue in traditional Chinese medicine (TCM) of which exceed maximum residue limit frequently occurred these years. It may be due to the pollution of environment and the lack of management in planting. Not only the medication safety, but also the reputation of TCM was severely affected by pesticide residues pollutants. The development and export trade have been curbed by these adverse events. With the rapid development of detecting techniques and methods, pesticide residue in TCM, as the chief exogenous contamination, is drawing increasingly attention worldwide, especially USA, Japan, South Korea and Germany who are now leading the detection of multi-pesticides residue and the pesticide security control technique. China is comparatively fall behind in this field. Therefore, it's very important to develop scientific and suitable methods to control the multi-pesticide residue in TCM. The object of this study is to establish a pretreatment platform and a gas chromatography–mass spectrometry (GC-MS) method for simultaneous determination of 198 pesticides in TCM, four aspects of this study are as follows:1. To select the detecting index in TCM. There are about one thousand kinds of pesticides have been registered in European Union. It's not necessary and possible to detect all kinds of pesticides. According to investigate the using status of pesticide in TCM planting and consult the documents, the producing conditions of pesticide in our country and the detecting standard in and out of China ware summarized. At last, 198 kinds of representative pesticides have been chosen as the detecting index in our study.2. To establish a pretreatment platform for simultaneous determination of 198 pesticides in TCM. The pretreatment of multi-residues include several steps, such as sampling, extraction, clean-up and concentration. The pretreatment is a complicated precoess because of the different compositions and variable matrix in TCM. As a result, it's impossible to develop a method which could analysis multi-residues in TCM in a single run. Gel permeation chromatography (GPC) and solid-phase extraction (SPE) were chosen as the main clean-up techniques. The parameter of GPC and SPE method, such as elute solvent and elute volume was optimized. Different clean-up methods for Chinese herbs were chosen according to the medicine matrix and pesticide characters to form pretreatment platform. Four Chinese herbs (including rhizome dioscoreae, radix astragali, fols lonicerae japonicae and pericarpium citri reticulatae) were used to evaluate the accuracy of this method. The samples were extracted with acetone follwing by the clean-up by GPC or the combination of GPC with SPE. The recoveries of most pesticides were ranged from 70% to 110% with the relative standard deviations (RSD) being from 2.7% to 13.6%(n=9).3. To develop a gas chromatography-mass spectrometry (GC-MS) method by adding analyte protectants to reduce the matrix-induced enhancement effect. The phenomenon known as"matrix-induced enhancement effect"is not only observed in the analysis of pesticides in food, but also in Chinese herbs. The quantification accuracy is seriously affected by matrix effect. Compared with standard calibration methods, the procedure with adding analyte protectants offers a more convenient and effective route to solve this problem. In this study, 198 types of pesticides in Chinese herbs have been analyzed by GC-MS, and the compounds that are susceptible to matrix effect were picked up and confirmed. I n addition, seven analyte protectants were evaluated and the most effective combination was determined. D-ribonic acid-γ-lactone (2mg/ml) and D-sorbitol (1mg/ml) were shown to be the best analyte protectants for the analysis of most pesticides. Present of proposed analyte protectants can reduce the quantitative error by overcome matrix effect in GC-MS. Moreover, the using of analyte protectants improved the chromatographic peak shape, lower the limit of quantification. What's important, this method is a technical breakthrough in pesticide analysis.4. To screening test of the samples collected. 198 types of pesticides in 120 types 333 kinds of TCM have been determined by using the detecting and pretreatment platform we have proposed. We summarized the current condition of pesticide residues pollutants in TCM and set the species of herbs and the detecting index by analysis the result. As a result, maximum residue limit (MRL) for some pesticides has been proposed according to toxicity date of pesticides proposed by WHO/FAO and current standard in and out of China.This study is part of the subject"Technical standards platform on detection of harmful residues in TCM"and is supported by the key project on Major Drug Discovery (Ggrant No.: 2009ZX09308-006) from the Ministry of Science and Technology, P.R.China.