| Contamination of traditional Chinese herbs with pesticide residues has caught more and more concern worldwide. If absorbed and reached to a poisonous dose, they impair human’s health seriously. This phenomenon has not only seriously affected the safety of traditional herbs but also become a big barrier for the herbs to entry the global markets. In recent years, more and more pesticides and their metabolites are constantly required to be tested in different countries in order to protect the herbs. With the improvement of foreign technical barriers, it is on the increase that the number of test items of which traditional Chinese herbs for import and export should be tested in more courtiers and governments like EU, Japan and other countries. Especially after implementation of the Positive list system in Japan, the pesticide residue needs more strict standards and lower MRL continuously, which greatly restricts the export of Chinese herbal medicine. This article would like to develop and build a quick analytical method to detect pesticide and their metabolites multiresidue in traditional Chinese herbs.The paper includes two chapters and the first part is to establish a method using QuEChERS cleanup followed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for quantitative determination of92pesticides and their metabolites multiresidues in Chinese herbs. The pesticide residues were extracted from the samples by acetonitrile containing1%acetic acid, cleaned up with PSA and then analyzed using LC-MS/MS in multiple reaction monitoring (MRM) mode with positive electrospray ionization. The analytical column was Shim-pack XR-ODS Ⅱ (2.0mm×75mm), the flow was200μl/min and the mobile phase was water with0.05%formic acid(A) and acetonitrile(B) using gradient elute, the gradient elute was the intial A was65%, then changed to40%in3.0min and lasted for3.0min, then changed to1%in3min lasted for5min,finally returned to65%in0.5min for2min. The limits of quantification (S/N≥10) of92pesticides were0.0990～7.54μg/kg and the limits of detection (S/N≥3) were0.0200～2.74μg/kg; each pesticide had fine linear responses with r≥0.999. The low recoveries ranged from70.3～138%with the relative standard deviation were between0.70～28%, the medium recoveries were70.3～138%and RSD%were1.2-24%, the high recoveries ranged from70.1～139%and RSD%were0.50-7.0%. Compared with the traditional method of pesticide residues, QuEChERS method was simple and fast with92pesticides and their metabolites can be detected in just15min. The results demonstrated that the method was simple, fast and sensitive to meet the requirements for the determination of92pesticides and their metabolites multiresidues in traditional Chinese herbs.In the second chapter of this thesis a method for simultaneous determination of19pesticides residues by gas chromatography with electron capture detector (GC-ECD) was proposed. By studying factors relating extraction recoveries, such as extraction solvent, extraction time, solid phase extraction column and type and volume of elution solvent, and so on, the pre-treatment conditions were established. The pesticide residues were extracted from the samples by acetonitrile containing1%acetic acid, cleaned up with Florisil SPE and used n-hexane:acetone (9:1) as eluent solvent then analyzed using GC-ECD. The analytical column was Rtx-5capillary commn(30m×0.25mm×0.25μm) with temperature programming which in initial time was60℃,then heating to150℃by the rate of15℃/min, then to200℃for2minute by the rate of5℃/min, then to250℃by3℃/min, finally to300℃by10℃/min for6minutes. The inlet temperature was280℃, the dector was300℃and column flow was1.0mL/min. The limits of quantification (S/N≥10) of19pesticides were0.0200-1.04mg/kg and the limits of detection (S/N≥3) were0.00400-0.208mg/kg; each pesticide had fine linear responses with r≥0.99and the average recoveries in spiked herbs ranged from67.4～130%with the relative standard deviation were below20%. The result of the method validation suggests the method is simple, quick and precise and can be suitable for detecting pesticide multiresidue in traditional Chinese herbs quickly.The two methods can be successfully applied in the5traditional Chinese herbs including Radix Glycyrrhizae, Radix Panacis Quinquefolii, Salvia miltiorrhiza, Radix Notoginseng and Panax ginseng C. Among detected herbs, all of43samples were detected pesticide residues and each sample exited multi-residues; there were49pesticides detected between the111pesticides and the amount of residues was below0.5mg/kg by the method. The article developed a quick method detecting111pesticides and their metabolites in traditional Chinese herbs. |
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