Jiang Hongliang, Somogyi Arpád, Timmermann Barbara N, Gang David R
Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA.
Rapid Commun Mass Spectrom. 2006;20(20):3089-100. doi: 10.1002/rcm.2699.
The gingerols, including [6]-, [8]-, and [10]-gingerols, a series of chemical homologs differentiated by the length of their unbranched alkyl chains, have been identified as major active components in fresh ginger rhizome. The purpose of this study was to investigate the utility of ion trap liquid chromatography/tandem mass spectrometry (LC/MS/MS) as an online tool to identify and quantify these compounds in raw or processed ginger rhizome samples. Negative mode electrospray ionization (ESI) was used in MS, MS/MS and MS(n) experiments in quadrupole ion trap instruments from two different manufacturers and in high-resolution and accurate mass MS and MS/MS experiments in a Fourier transform ion cyclotron resonance mass spectrometer to elucidate the ionization and fragmentation mechanisms of these compounds in these instruments. Positive mode ESI, which generated many more fragment ions in full scan MS even under gentle ionization conditions, was also used in LC/MS and MS/MS experiments and in direct infusion MS and MS/MS experiments. Consistent and predictable ionization and fragmentation behaviors were observed for all gingerols when analyzed in the same instrument. Instruments from different manufacturers, however, had different ionization mechanisms. The major difference between instruments was their ability to form covalent dimer adducts of the gingerols. Subsequent fragmentation patterns of the precursor ions were essentially identical. These results clearly demonstrate that LC/MS instruments produce data that cannot necessarily be replicated in other laboratories, especially if those laboratories do not have the same instrument model from the same manufacturer. This presents major problems for metabolite target analysis, metabolic profiling and metabolomics investigations, which would benefit from LC/MS mass spectrum libraries as they do from GC/MS mass spectrum libraries, because such libraries may not be valid across platforms.
姜辣素，包括[6]-、[8]-和[10]-姜辣素，是一系列通过其直链烷基链长度区分的化学同系物，已被确定为新鲜姜根茎中的主要活性成分。本研究的目的是研究离子阱液相色谱/串联质谱法（LC/MS/MS）作为一种在线工具，用于鉴定和定量生的或加工过的姜根茎样品中的这些化合物。在来自两家不同制造商的四极杆离子阱仪器的MS、MS/MS和MS(n)实验中，以及在傅里叶变换离子回旋共振质谱仪的高分辨率和精确质量MS和MS/MS实验中，使用负模式电喷雾电离（ESI）来阐明这些化合物在这些仪器中的电离和碎裂机制。正模式ESI在全扫描MS中即使在温和的电离条件下也会产生更多的碎片离子，也用于LC/MS和MS/MS实验以及直接进样MS和MS/MS实验。当在同一仪器中分析时，所有姜辣素都观察到一致且可预测的电离和碎裂行为。然而，来自不同制造商的仪器具有不同的电离机制。仪器之间的主要差异在于它们形成姜辣素共价二聚体加合物的能力。前体离子的后续碎裂模式基本相同。这些结果清楚地表明，LC/MS仪器产生的数据不一定能在其他实验室中复制，特别是如果那些实验室没有来自同一制造商的相同仪器型号。这给代谢物靶向分析、代谢谱分析和代谢组学研究带来了重大问题，这些研究将从LC/MS质谱库中受益，就像它们从GC/MS质谱库中受益一样，因为这样的库可能在不同平台上无效。
