Study On Determination Of Organic Pesticide Residues In Chinese Herbal Medicine

Chinese herbal medicine(CHM), as a special plant, plays an important part in the health of the Chinese. The requirement of CHMs is on the increase, resultingly the cultivation of CHMs is depended on manpower. Because pesticides are applied to a broad variety of CHMs to reduce loss from insects, CHMs have a high risk of contamination of pesticides. So it is very important to strengthen the study on determination of pesticide residues in CHMs. Recent years, organochlorine pesticide (OCP) is the main study, which falls short of the factual contamination in CHMs. Referred to a lot of literatures, this paper explored a series of experiment methods such as extraction, purification and analytical techniques in samples. Methods for the determination of multi-residue pesticides in Chinese herbal medicines were investigated. The main contains as follows:1. A method for the determination of 13 organophosphorous and organonitrogen pesticide residues in Chinese herbal medicine was investigated. Pesticide residues were extracted from Chinese herbal medicine samples with a mixture solvent. Extracts were cleaned up with a column filled with Florisil and neutral alumium oxide, and determined by gas chromatography-mass spectrometry. The recoveries obtained from Angelicae Dahurica at two concentration levels, 0.1 and 0.05 mg of pesticide per kg sample, were in the ranges of 81.2%-117.5% and 88.5-119.3%, with relative standard deviations of 4.00%-9.88% and 5.66%-9.50%. Detection sensitivity can be significantly increased and interference from impurities can be excluded by using selective ionic monitoring technique. The method was proved to be effective and practical.2. A method was developed for the determination of 11 organchlorine pesticide residues in Chinese herbal medicine by the capillary gas chromatography with the electron capture detector(CGC-ECD).Sonication extraction system was used, in which acetone was the extractant. The solvent of sodium chloride was added to the extractant to separate the pesticides, n-Hexane was also added to carry out liquid-liquid extraction. The extracts were cleaned up by concentrated H₂SO₄.The recoveries obtained from samples were in the range of 72.5%-123.5%, with relative standard deviations of 1.04%-9.82%.The method was proved to be effective and practical.3. A method was developed for the determination of some polar pesticides and their main metabolites, such as aldicarb. aldicarb sulphoxide. aldicarb sulphone, carbofuran and 3-hydroxicarbofuran, in Chinese herbal medicines has been developed. Pesticides were isolated by Hypersil ODS with acetonitrile and H2O(30:70. V/V) as the mobile phase. Residues were extracted by acetonitrile -methanol. Extracts were cleaned up with a column filled with Florisil and neutral aluminum oxide. and determined by high performance liquid chromatography with Diode-array detector. The average recoveries obtained from samples were in the range of 72.7%-107.0%, with relative standard deviations of 1.03%-7.51%. the recovery and repeatabilityindicate that the proposed method is well suitable for monitoring carbamate pesticide in CHMs.