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    色谱-串联质谱法测定中药材中33种禁用农药残留量的方法探讨

    Discussion on Determination of Residues of 33 Forbidden Pesticides in Chinese Medicinal Materials by Chromatography-Tandem Mass Spectrometry

    • 摘要: 采用固相萃取法和QuEChERS法处理样品,以高效液相色谱-串联质谱法(HPLC-MS/MS)和气相色谱-串联质谱法(GC-MS/MS)测定中药材中33种禁用农药残留量,对不同前处理方法、不同检测手段结果的差异性进行了探讨。固相萃取法操作步骤如下:称取样品粉末5 g和氯化钠1 g,用50 mL乙腈重复提取两次,合并上清液,减压浓缩至1~3 mL,再用乙腈定容至10 mL;取上述提取液4 mL于装有石墨化碳黑的氨基复合固相萃取小柱中,用25 mL体积比为3∶1的乙腈-甲苯混合液洗脱,洗脱液于40℃水浴浓缩至近干,加入0.02 mL内标溶液和2 mL乙腈,用0.22 μm有机滤膜过滤,取滤液待测。QuEChERS法步骤如下:称取样品粉末3 g于50 mL聚苯乙烯具塞离心管中,用15 mL 1%(体积分数)冰乙酸溶液溶解、15 mL乙腈提取后,再加入7.5 g质量比为4∶1的无水硫酸镁-无水乙酸钠混合粉末,用装有400 mg N-丙基乙二胺/400 mg C18吸附剂/200 mg石墨化碳黑/1 200 mg硫酸镁的净化管净化,吸取上清液5 mL,于40℃水浴浓缩至近干,加入0.01 mL内标溶液,再用乙腈稀释至1 mL后待测。HPLC-MS/MS采用外标法定量,GC-MS/MS采用内标法定量。结果显示:33种农药及其异构体或氧类似物标准曲线的线性范围为5~200 μg·L-1(HPLC-MS/MS)或10~200 μg·L-1(GC-MS/MS),检出限为0.002 8~3.0 μg·kg-1(HPLC-MS/MS)或1.4~3.2 μg·kg-1(GC-MS/MS);对阴性黄芩样品进行3个浓度水平的加标回收试验,回收率为54.8%~128%,测定值的相对标准偏差(n=6)为0.99%~21%。方法用于分析黄芩片、紫苏叶、黄苓、黄柏、小茴香、当归、半夏、山麦冬等8种样品,主要检出有机磷和氨基甲酸酯两类农药,并且黄苓中甲基异柳磷、小茴香中甲拌磷和克百威、半夏中水胺硫磷的检出量均超出药典限值。

       

      Abstract: The samples were treated by solid phase extraction and QuEChERS method, and the residues of 33 forbidden pesticides in Chinese medicinal materials were determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). The differences of the results of different pretreatment methods and different detection methods were discussed. The operation steps of solid phase extraction were as follows. The mixture of sample powder (5 g) and sodium chloride (1 g) was extracted twice with acetonitrile (50 mL). The supernatant combined was concentrated to 1-3 mL under reduced pressure, and then made its volume up to 10 mL with acetonitrile. The above extraction solution (4 mL) was put onto an amino composite solid phase extraction small column with graphitized carbon black, eluted with a mixture (25 mL) of acetonitrile and toluene at volume ratio of 3:1, and concentrated to nearly dry in a water bath at 40℃. The residue was added into internal standard solution (0.02 mL) and acetonitrile (2 mL), and the mixture was filtered with 0.22 μm organic filter membrane. The filtrate was obtained for test. The operation steps of QuEChERS method were as follows. The sample powder (3 g) was put into a 50 mL-polystyrene centrifuge tube with stopper, dissolved with 1% (φ) glacial acetic acid solution (15 mL), extracted with acetonitrile (15 mL), and a mixed powder (7.5 g) of anhydrous magnesium sulfate and anhydrous sodium acetate at mass ratio of 4:1 was added. The above solution was purified with a purification tube containing 400 mg of N-propylethylenediamine, 400 mg of C18 adsorbent, 200 mg of graphitized carbon black and 1 200 mg of magnesium sulfate. The supernatant (5 mL) was absorbed, concentrated to nearly dry in a water bath at 40℃. The residue was added into internal standard solution (0.01 mL), and the mixture was diluted to 1 mL with acetonitrile for test. External standard method was used for quantitative analysis on HPLC-MS/MS, and internal standard method was used for quantitative analysis on GC-MS/MS. It was shown that linear ranges of standard curves of 33 pesticides and their isomers or oxygen analogues were 5-200 μg·L-1 (HPLC-MS/MS) or 10-200 μg·L-1 (GC-MS/MS), with detection limits in the ranges of 0.002 8-3.0 μg·kg-1 (HPLC-MS/MS) or 1.4-3.2 μg·kg-1 (GC-MS/MS). Recovery test was made on the negative Radix Scutellariae sample by standard addition method, giving results in the range of 54.8%-128%, and RSDs (n=6) of the determined values were ranged from 0.99% to 21%. This method was used for analysis of 8 kinds of samples, including Radix Scutellariae, Folium Perillae, Scutellaria lateriflora, Cortex Phellodendri, Fructus Foeniculi, Radix Angelicae sinensis, Rhizoma Pinelliae and Radix Liriopes. Organophosphorus and carbamate pesticides were mainly detected, and the detection amounts of isofenphos-methyl in Scutellaria lateriflora, phorate and carbofuran in Fructus Foeniculi and isocarbophos in Rhizoma Pinelliae were exceeded the limits of pharmacopoeia.

       

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