目的 建立大鼠ig炙甘草汤后体内甘草次酸的LC-MS/MS测定方法。方法 采用醋酸乙酯沉淀蛋白处理血浆样品，选用白藜芦醇为内标，采用LC-MS/MS法测定，色谱条件为ORBAX SB-C₁₈反相色谱柱（Agilent，50 mm×2.1 mm，1.8 μm），乙腈-水（80∶20，含0.2%甲酸）为流动相，体积流量0.2 mL/min，柱温30 ℃。样品经电喷雾离子（ESI）源负离子化后，通过Agilent 6410三重四级杆串联质谱仪，采用多反应监测（MRM）对甘草次酸进行测定，分别选用m/z 469.4→425.4和227.1→143.0作为甘草次酸和内标物白藜芦醇的检测离子对。结果 甘草次酸在33.4～8 560.0 ng/mL线性关系良好（R²＝0.997 1），日内（n＝6）、日间（n＝6）精密度、稳定性RSD均小于10%。甘草次酸高、中、低3个质量浓度平均提取回收率分别为75.3%、78.2%、78.5%。在此方法下得到大鼠ig炙甘草汤后血浆中甘草次酸的药动学参数分别为t_max＝（8.00±1.13）h，C_max＝（811.02±300.25）ng/mL，AUC_0～24＝（11 439.21±3 367.36）ng/mL·h。结论 该方法灵敏、准确、快速、选择性高，可用于甘草次酸血药浓度监测和药动学研究。

Objective To establish an LC-MS/MS method for determination of glycyrrhetinic acid (GA) in plasma after ig administration of Glycyrrhizae Radix et Rhizoma Praeparata Cum Melle (Zhigancao) Decoction in rats in vivo. Methods Treating plasma with ethyl acetate protein precipitation and taking reseveratrol was used as the internal standard (IS), the residues were analyzed with LC-MS/MS system (Agilent ORBAX SB-C₁₈ RP column, 50 mm × 2.1 mm, 1.8 μm) with the mobile phase consisted of acetonitrile-water (80 : 20, 0.2% formic acid), flow-rate of 0.2 mL/min, and column temperature of 30 ℃. Agilent 6410 triple quad mass spectrometer system with an electrospray ionization (ESI) source and negative ion mode was used as the detector in this study. Multi-reaction monitoring (MRM) was used to detect GA by using ion combinations of m/z 469.4→425.4 for GA and 227.1→143.0 for IS. Results The calibration curve showed good linear regression (R² = 0.997 1) within measurement ranges (33.4—8 560.0 ng/mL). Both the intra- and inter-day precision and variation RSD were less than 10%. The average recovery rates at low, medium, and high concentrations of GA were 75.3%, 78.2%, and 78.5%, respectively. Under these conditions, the pharmacokinetic parameters of GA in plasma of rats after ig administration of Zhigancao Decoction were t_max (8.00 ± 1.13) h, C_max (811.02 ± 300.25) ng/mL, and AUC_0-24 (11 439.21 ± 3 367.36) ng/mL·h. Conclusion The method provides a sensitive, accurate, precise, and reliable analytical procedure for detecting GA in rat plasma and studying its pharmacokinetics.

国家“十一五”科技支撑计划资助项目（2006BAI08B04-10）