Draisci R, Marchiafava C, Palleschi L, Cammarata P, Cavalli S
Laboratorio Medicina Veterinaria, Istituto Superiore di Sanità, Rome, Italy.
J Chromatogr B Biomed Sci Appl. 2001 Apr 5;753(2):217-23. doi: 10.1016/s0378-4347(00)00544-2.
A new method for the rapid extraction and unequivocal confirmation of two highly potent fluorinated synthetic corticosteroids, dexamethasone and its beta-epimer betamethasone, in bovine liver was developed. Flumethasone was used as internal standard. An extraction procedure using an accelerated solvent extraction system was employed for the isolation of the analytes in liver samples. The procedure was highly automated, including defatting and extraction steps, sequentially carried out under 1.0 x 10(4) kPa in about 35 min. The extracts were then directly analysed by tandem mass spectrometry with on-line liquid chromatography. The analytes were ionised in a heated nebulizer interface operating in the negative ion mode where the molecular related ions [M-H-CH2O]- were generated for each analyte, at m/z 361 for betamethasone and dexamethasone and at m/z 379 for flumethasone. They served as precursor ions for collision-induced dissociation and three diagnostic product ions for the drugs were identified to carry out analyte confirmation by selected reaction monitoring. Assessment of recovery, specificity and precision for betamethasone, dexamethasone and flumethasone proved the method suitable for confirmatory purposes. The limit of quantification of betamethasone and dexamethasone in liver tissue was 1.0 microg/kg.
开发了一种用于快速提取和明确确认牛肝中两种高效氟化合成皮质类固醇（地塞米松及其β-差向异构体倍他米松）的新方法。氟米松用作内标。采用加速溶剂萃取系统的萃取程序来分离肝脏样品中的分析物。该程序高度自动化，包括脱脂和萃取步骤，在1.0×10⁴ kPa下约35分钟内依次进行。然后将提取物直接通过在线液相色谱串联质谱进行分析。分析物在加热雾化器接口中以负离子模式电离，每种分析物产生分子相关离子[M - H - CH₂O]⁻，倍他米松和地塞米松的m/z为361，氟米松的m/z为379。它们用作碰撞诱导解离的前体离子，并鉴定出三种药物的诊断产物离子，通过选择反应监测进行分析物确认。对倍他米松、地塞米松和氟米松的回收率、特异性和精密度评估证明该方法适用于确证目的。肝组织中倍他米松和地塞米松的定量限为1.0 μg/kg。
