Direct analysis of sterols by derivatization matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and tandem mass spectrometry
作者:Iyad Hailat、Robert J. Helleur
DOI:10.1002/rcm.6766
日期:2014.1.30
resulting in diagnostic derivative fragments at m/z 146.03 and 96.89, respectively. Cleavage of the ether bond of N-methylpyridyl ethers gave a diagnostic fragment ion at m/z 110.04. Sterol profiles in mussels obtained by MALDI-TOFMS were in close agreement with those obtained by GC/MS. Two sterols (cholesterol and β-sitosterol) were selected for quantification as their sulphated and picolinyl esters. Calibration
原理游离固醇是中性分子,很难用MALDI或ESI分析,其分子离子容易碎裂。为了提高其电离效率和选择性,固醇通过不同的试剂衍生化。方法将选定的甾醇转化为其相应的吡啶啉酯,N-甲基吡啶基醚和硫酸酯。该衍生物通过矩阵的适当选择为MALDI-TOFMS分析而优化。进行了MALDI-TOF / TOF实验以研究衍生物的断裂途径及其在结构解析中的用途。贻贝的脂质提取物用作测试样品,对生物样品中的固醇进行MALDI分析,并通过GC / MS进行分析以进行比较。结果甾醇吡啶甲基酯被鉴定为磺化加合物[M + Na](+),加入乙酸钠(20 mM)后信号明显增强。甾醇N-甲基吡啶基醚很容易检测为[M](+),而硫酸固醇最好检测为[MH](-)。甲基吡啶基酯和硫酸酯的酯键在MS / MS中容易断裂,分别导致m / z 146.03和96.89的诊断衍生物片段。N-甲基吡啶基醚的醚键的裂解给出了m / z 110