Comprehensive lipidomic analysis of human plasma using multidimensional liquid- and gas-phase separations: Two-dimensional liquid chromatography–mass spectrometry vs. liquid chromatography–trapped-ion-mobility–mass spectrometry

Abstract

Recent advancements in separation science have resulted in the commercialization of multidimensional separation systems that provide higher peak capacities and, hence, enable a more-detailed characterization of complex mixtures. In particular, two powerful analytical tools are increasingly used by analytical scientists, namely online comprehensive two-dimensional liquid chromatography (LC×LC, having a second-dimension separation in the liquid phase) and liquid chromatography-ion mobility-spectrometry (LC-IMS, second dimension separation in the gas phase). The goal of the current study was a general assessment of the liquid-chromatography-trapped-ion-mobility-mass spectrometry (LC-TIMS-MS) and comprehensive two-dimensional liquid chromatography-mass spectrometry (LC×LC-MS) platforms for untargeted lipid mapping in human plasma. For the first time trapped-ion-mobility spectrometry (TIMS) was employed for the separation of the major lipid classes and ion-mobility-derived collision-cross-section values were determined for a number of lipid standards. The general effects of a number of influencing parameters have been inspected and possible directions for improvements are discussed. We aimed to provide a general indication and practical guidelines for the analyst to choose an efficient multidimensional separation platform according to the particular requirements of the application. Analysis time, orthogonality, peak capacity, and an indicative measure for the resolving power are discussed as main characteristics for multidimensional separation systems.

Merging metabolomics and lipidomics into one analytical run

“…4,6 To date, comprehensive two-dimensional separations are not widely spread in both fields. 25,26 A successful alternative analytical strategy addressed multiple-tailored derivatization methods targeting different chemical moieties thereby covering the whole metabolome while at the same time allowing to resort to a single reversed phase separation. [27][28][29] However, in these studies, lipids are largely omitted.…”

Recent advances in analytical strategies for mass spectrometry-based lipidomics

“…evaluated LC-IMS-MS and LC LC-MS-based untargeted lipidomic performances in terms of the number of molecular features, analysis time and structural characterization. From this study, one can see that although a higher number of identified lipids were obtained in LC LC-MS through improving the separation of co-eluting lipids, LC-IMS-MS is overperformed in the faster analysis and accurate lipid identification [ 44 ]. It is recommended to complement the advantages of both techniques for untargeted lipidomics of large-scale complex samples, i.e., conducting comprehensive lipids profiling on the LC LC-MS platform followed by IM-MS for detailed structural characterization [ 44 ].…”

Evaluation of LC-MS and LC×LC-MS in analysis of zebrafish embryo samples for comprehensive lipid profiling

“…Based on previous studies [45,46], the orthogonality of comprehensive 2DLC systems was estimated by a surface coverage method (see ESM). Rather than using several lipid standards [29], all annotated lipids were included in the component pool and used to calculate the coverage metric because the size of analytes in the LC×LC separation really influences the values of orthogonality [47]. To simplify the calculation, several vectors [37] were introduced to compute the effective area of surface coverage which was, as is seen from Fig.…”

“…To our knowledge, this is the first study on the development and application of 2DLC-MS lipidomics approaches in zebrafish. However, 2DLC-MS lipidomics has been used in other fields such as human plasma [27][28][29][30] and plants [31,32]. The aim of this study was to optimize a variety of LC×LC-MS methods based on C18×HILIC, HILIC×C18, and HILIC×PFP, using the lipid classes found in zebrafish embryos.…”