Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry.
Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry.
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使用激光诱导声解吸/化学电离、大气压化学电离和电喷雾电离质谱表征非极性脂质和选定的类固醇。
DOI：
10.1016/j.ijms.2010.11.001
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发表时间：
2011
影响因子：
1.8
通讯作者：
Kenttämaa,HilkkaI
中科院分区：
文献类型：
--
作者：
Jin,Zhicheng;Daiya,Shivani;Kenttämaa,HilkkaI
在傅里叶变换离子回旋共振质谱仪（FT-ICR）中，采用激光诱导声解吸（LIAD）结合ClMn(H{sub 2}O){sup +}化学电离（CI）方法分析了非极性脂类和选定的甾体。所研究的非极性脂类，胆固醇、5α-胆甾烷、胆甾-3,5-二烯、角鲨烯和β-胡萝卜素，在与ClMn(H{sub 2}O){sup +}离子反应后，均能单独形成所需的水替代产物（加合物-H{sub 2}O）。甾体激素、雄酮、脱氢表雄酮（DHEA）、雌酮、雌二醇和雌三醇也能形成丰富的加合物- h {sub 2}O离子，但也观察到较少的加合物- 2h {sub 2}O离子。（+）APCI和（+）ESI均不能电离饱和烃脂质-胆甾烷。APCI成功地电离了不饱和烃脂质，形成完整的质子化分析物。然而，它会导致胆固醇和类固醇的广泛分裂。最坏的情况是胆固醇不能产生任何稳定的质子化分子。另一方面，ESI不能电离任何烃分析物，无论是饱和的还是不饱和的。然而，除了胆固醇和雌酮外，ESI可用于质子化含氧分析物，在所有情况下都比APCI的碎片化少得多。综上所述，LIAD/ClMn(H{sub 2}O){sup +}化学电离比APCI和ESI更适合于非极性脂质和甾体的质谱分析。
Laser-induced acoustic desorption (LIAD) combined with ClMn(H{sub 2}O){sup +} chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5α-cholestane, cholesta-3,5-diene, squalene, and β-carotene, were found to solely form the desired water replacement product (adduct-H{sub 2}O) upon reaction with the ClMn(H{sub 2}O){sup +} ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H{sub 2}O ions, but less abundant adduct-2H{sub 2}O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H{sub 2}O){sup +} chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids.