Bulbus Fritillaria (BF) ,one of the derivatives from the plant of various Frit‐illaria species ,has been commonly used as expectorant and antitussive herb in tradition‐al Chinese medicine .The value of BF is relative related to its quality ,however ,there is no reliable method to evaluate its quality .Therefore ,it is necessary to develop a rapid and reliable method for classification of species of BF .In this study ,the QuEChERS (quick ,easy ,cheap ,effective ,rugged ,and safe) as sample preparation method and combined with liquid chromatography‐tandem mass spectrometry (LC‐MS/MS ) was proposed to determine trace alkaloids of BF . T he main bioactive isosteroidal alkaloids analyzed are peimine ,peiminine and peimisine .The extraction efficiency of QuEChERS were systematically studied and the optimal extraction conditions were as follows :extraction of three alkaloids by using 3 mL extraction solution of ethyl acetate‐water (75∶25 ,V/V ) w hich is containing 3% ammonium hydroxide and 1 g of ammonium carbonate ,and then mixing by vortex condition for 5 min .The extract was cleaned with 10 mg of anhydrous magnesium sulfate and 20 mg of florisil .The extracted isosteroidal alkaloids were analyzed by liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS ) . The quantification was performed by extracted ion chromatography and MS/MS spectra was applied for identification of isosteroidal alka‐loids .T he linear range for peimisine is from 0.1 to 20 μg/g and for peiminine and peimine are from 0.05 to 10μg/g with coefficients of determination (R2 ) above 0.992 3 . The limit of detection (LODs) of the proposed method range from 0.005 to 0.03 μg/g . Intra‐day and inter‐day precisions represented in RSD% are in a range of 1.1%‐17.5% . The recoveries are in a range of 89.6%‐97.0% .The amount of peimisine ,peiminine , peimine in a real Chuan‐Beimu sample were detected by the proposed method and the amount are at 4.35 ,0.92 ,1.39 μg/g ,respectively .%川贝母具有止咳化痰之功效，是经济价值较高的药品，因此市场上偶有将低价格贝母掺入其中的行为，因此需要建立一种快速有效的方法用于贝母中异甾体生物碱的分析。本研究采用QuEChERS前处理技术萃取川贝母样品中贝母辛、贝母乙素及贝母甲素等异甾体生物碱，并结合液相色谱‐串联质谱法（LC‐MS／MS）进行分析。在QuEChERS优化条件下，取0.5 g贝母样品，添加3 mL含3％氨水的乙酸乙酯‐水溶液（75∶25，V／V ），再加入1 g 碳酸铵，振荡5 min后，以4000 r／min离心5 min ，取1.8 mL上清液，加入20 mg硅酸镁及10 mg无水硫酸镁，并以14000 r／min离心3 min ，氮气吹干后，用20％甲醇水溶液定量至1 mL ，采用LC‐MS／MS法在正离子扫描模式下检测。结果表明：川贝母样品中贝母辛的线性范围为0.1～20μg／g ，贝母乙素和贝母甲素的线性范围为0.05～10μg／g ；线性相关系数（ R2）大于0.9923；检测限为0.005～0.03μg／g ；日内与日间精密度的相对标准偏差介于1.1％～17.5％之间；回收率介于89.6％～97.0％之间。应用此方法检测真实样品，测得的异甾体生物碱含量中贝母辛为4.35μg／g ，贝母乙素为0.92μg／g ，贝母甲素为1.39μg／g。该方法具有前处理简便快速，样品和有机溶剂用量少等优点，可为其他贝母中生物碱的检测提供方法参考。
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