Zhang H, Henion J, Yang Y, Spooner N
Analytical Toxicology, Cornell University, Ithaca, New York 14850, USA.
Anal Chem. 2000 Jul 15;72(14):3342-8. doi: 10.1021/ac000089r.
Atmospheric pressure ionization time-of-flight mass spectrometry coupled with high-performance liquid chromatography was used to characterize the in vitro metabolites of glyburide. Metabolic products formed in vitro by human microsomes were separated using a C18 column with gradient elution at a flow rate of 200 microL/min without postcolumn splitting. In-source collision-induced dissociation (CID) by automated nozzle potential switching was employed to obtain both abundant protonated molecules and characteristic fragments whose accurate masses were measured simultaneously by internal mass calibration, performed by continuous postcolumn infusion of two reference standards. The mass errors were within 9 ppm for all ions measured, whose abundance was greater than 5%, relative to the most abundant isotopic "A" ion. Exact mass differences between the parent drug and metabolite(s) were determined and these values corresponded to a unique elemental composition. The elemental compositions of all metabolite fragment ions were generated based upon the known compositional elements of the protonated molecule. The structures of metabolites and their fragment ions were proposed based on the determined elemental composition and in-source CID spectra. The elemental composition and fragmentation pathways of four cyclohexyl hydroxylation metabolites and one ethylhydroxy metabolite are discussed.
采用大气压电离飞行时间质谱联用高效液相色谱法对格列本脲的体外代谢产物进行表征。使用C18柱，以200微升/分钟的流速进行梯度洗脱，无需柱后分流，分离人微粒体在体外形成的代谢产物。采用自动喷嘴电位切换进行源内碰撞诱导解离（CID），以获得丰富的质子化分子和特征性碎片，通过连续柱后注入两种参考标准物进行内标质量校准，同时测量其精确质量。对于所有丰度大于5%的离子，相对于最丰富的同位素“A”离子，质量误差在9 ppm以内。确定了母体药物与代谢产物之间的精确质量差异，这些值对应于独特的元素组成。基于质子化分子的已知组成元素生成所有代谢产物碎片离子的元素组成。根据确定的元素组成和源内CID光谱推测代谢产物及其碎片离子的结构。讨论了四种环己基羟基化代谢产物和一种乙基羟基代谢产物的元素组成和裂解途径。
