| Traditional Chinese medicine is one of the most valuable cultural heritages in China. Clinical effectiveness of the Chinese medicine is dependent on not only the specific components, but as well the quality of medicinal herbs. During the past several decades, public concern over pesticide residues, such as organochlorine, organophosphate, organonitrogen, pyrethroid as well as triazines in food and related commodities has been increasing. These pesticides, due to their high degree of toxicity, constitute a very important group of contaminants in food, particularly in medicinal herbs. Since the safety level of pesticide residues in foods increases with the development of living standard, the amount limit of pesticide residues in herbs demands much lower than ever before. Thus development of efficiently analytical method for determination of samples with a wide range and low concentrations of active ingredients is critical important.The thesis is focusing on the investigation of analytic methods of determining organochlorine, organophosphate and pyrethroid multi-residues in herbal medicine Chrysanthemum morifolium and Salvia miltiorrhiza by SPE-ECD, GC-EI-MS and GC-NCI-MS techniques.Microwave-assisted extraction with acetone-hexane (1:1,v/v) for 8 min at 60℃through orthogonal test and clean-up by ENVI-Carb SPE column in combination with LC-18 SPE column were proved to be a highly efficient method for clean-up and pre-concentration. The pre-treatment method of organochlorine pesticide residues was developed using GC-CGC-ECD. The calibration curves were within the range of 0.0025～0.5μg/mL, with correlation coefficients (R2) being 0.9990～0.9999. The recoveries and the CVs of the multiple pesticides of organochlorine obtained were in the range of 83.0～109.3% and 2.0—5.4%, respectively at three spiked level of 0.0025, 0.0125 and 0.05 mg/kg with LODs being 4.0×10-5～8.5×10-4 mg/kg. The accuracy and precision meet the need of pesticide residues analysis.A solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS/EI) method was established to determine nine types of organochlorine pesticides in Chrysanthemum morifolium. The calibration curves were in the range of 0.005～0.5μg/mL. The correlation coefficients (R2) were≥0.9981 except for PP'-DDT is 0.9928. The method is accurate, precise, simple and easy for operation. The recoveries were in the range of 71.8～112.2% and CVs≤8.2% at three spiked level of 0.005, 0.025 and 0.05 mg/kg with LODs being 2.0×10-4 mg/kg～1.5×10-3 mg/kg.Shaking extraction with acetone-hexane (6:4,v/v), purified and collected by solid-phase extraction, a multi-residues method for determining 12 types of pesticides in Salvia miltiorrhiza by capillary gas chromatography with ECD has been developed. The pesticide residues in Salvia miltiorrhiza were separated by SPB-5 capillary column under the condition of temperature-programmed run and ECD. Their calibration curves were in the range of 0.01～10 mg/L, with correlation coefficients (R2) ranging from 0.9922～0.9997. The recoveries and CVs of the pesticides were 76.8～104.0% and 1.11～2.50%, respectively. This method can decrease some interference like pigments, with LODs concentrations being 0.01～0.05 mg/kg.A solid phase extraction-gas chromatography-negative chemical ionization mass spectrometry (SPE-GC-MS/NCI) method was proposed for analyzing 12 kinds of pyrethroid pesticides in Herbal medicine Chrysanthemum morifolium. Pesticide residues were extracted from Chrysanthemum morifolium sample Microwave-assisted extraction with ethyl acetate, then cleaned-up by Graphitized carbon black SPE column in combination with Alumina neutral SPE column. Analytical screening was determined by the technique of gas chromatography-negative chemical ionization mass spectrometry-selected ion monitoring. Their calibration curves were in the range of 0.08～1.28μg/mL, with correlation coefficients (R2) ranging from 0.9989～0.9997. The method is reliable and stable and the recoveries of all pyrethroid pesticides were ranging from 70.4% to 112.4% at three spiked level, 0.016×10-3 mg/kg, 0.032×10-3 mg/kg and 0.064×10-3 mg/kg. The CVs were below 8.6%. This method is selective and sensitive, and the LODs of majority pyrethroid pesticides were about 1.0×10-3 mg/kg except for Permethrin 1.1×10-2 mg/kg and Tefluthrin 2.0×10-5 mg/kg. |
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