Ultrahigh-performance supercritical fluid chromatography-mass spectrometry (UHPSFC/MS) method is optimized for the high-throughput quantitation of lipids in human serum and plasma with an emphasis on robustness and accurate quantitation. Bridged ethylene hybrid (BEH) silica column (100 × 3 mm; 1.7 μm) is used for the separation of 17 nonpolar and polar lipid classes in 4.4 min using the positive ion electrospray ionization mode. The lipid class separation approach in UHPSFC/MS results in the coelution of all lipid species within one lipid class in one chromatographic peak, including two exogenous internal standards (IS) per lipid class, which provides the optimal conditions for robust quantitation. The method was validated according to European Medicines Agency and Food and Drug Administration recommendations. UHPSFC/MS combined with LipidQuant software allows a semiautomated process to determine lipid concentrations with a total run time of only 8 min including column equilibration, which enables the analysis of 160 samples per day.

• Keywords
• High-throughput lipidomics, Mass spectrometry, Plasma, Quantitation, Serum, Ultrahigh-performance supercritical fluid chromatography, Validation,
• MeSH
• Mass Spectrometry methods   MeSH
• Humans MeSH
• Lipidomics * methods   MeSH
• Lipids * analysis   blood   MeSH
• Chromatography, Supercritical Fluid * methods   MeSH
• Chromatography, High Pressure Liquid methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Lipids * MeSH

Reversed-phase ultrahigh-performance liquid chromatography-mass spectrometry (RP-UHPLC/MS) method was developed with the aim to unambiguously identify a large number of lipid species from multiple lipid classes in human plasma. The optimized RP-UHPLC/MS method employed the C18 column with sub-2-μm particles with the total run time of 25 min. The chromatographic resolution was investigated with 42 standards from 18 lipid classes. The UHPLC system was coupled to high-resolution quadrupole-time-of-flight (QTOF) mass analyzer using electrospray ionization (ESI) measuring full-scan and tandem mass spectra (MS/MS) in positive- and negative-ion modes with high mass accuracy. Our identification approach was based on m/z values measured with mass accuracy within 5 ppm tolerance in the full-scan mode, characteristic fragment ions in MS/MS, and regularity in chromatographic retention dependences for individual lipid species, which provides the highest level of confidence for reported identifications of lipid species including regioisomeric and other isobaric forms. The graphs of dependences of retention times on the carbon number or on the number of double bond(s) in fatty acyl chains were constructed to support the identification of lipid species in homologous lipid series. Our list of identified lipid species is also compared with previous publications investigating human blood samples by various MS-based approaches. In total, we have reported more than 500 lipid species representing 26 polar and nonpolar lipid classes detected in NIST Standard reference material 1950 human plasma.

• Keywords
• Human plasma, Lipidomics, Lipids, Mass spectrometry, Retention behavior, Reversed-phase, Ultrahigh-performance liquid chromatography,
• MeSH
• Chromatography, Liquid methods   MeSH
• Mass Spectrometry methods   MeSH
• Humans MeSH
• Lipids blood   chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Lipids MeSH

In the last 2 decades, lipidomics has become one of the fastest expanding scientific disciplines in biomedical research. With an increasing number of new research groups to the field, it is even more important to design guidelines for assuring high standards of data quality. The Lipidomics Standards Initiative is a community-based endeavor for the coordination of development of these best practice guidelines in lipidomics and is embedded within the International Lipidomics Society. It is the intention of this review to highlight the most quality-relevant aspects of the lipidomics workflow, including preanalytics, sample preparation, MS, and lipid species identification and quantitation. Furthermore, this review just does not only highlights examples of best practice but also sheds light on strengths, drawbacks, and pitfalls in the lipidomic analysis workflow. While this review is neither designed to be a step-by-step protocol by itself nor dedicated to a specific application of lipidomics, it should nevertheless provide the interested reader with links and original publications to obtain a comprehensive overview concerning the state-of-the-art practices in the field.

• Keywords
• LC-MS, MS, chromatography, ion mobility spectrometry, lipid identification, lipidomics, metabolomics, phospholipids, sphingolipids,
• MeSH
• Mass Spectrometry MeSH
• Humans MeSH
• Lipidomics * standards   MeSH
• Lipids analysis   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Lipids MeSH

Early detection of cancer is one of the unmet needs in clinical medicine. Peripheral blood analysis is a preferred method for efficient population screening, because blood collection is well embedded in clinical practice and minimally invasive for patients. Lipids are important biomolecules, and variations in lipid concentrations can reflect pathological disorders. Lipidomic profiling of human plasma by the coupling of ultrahigh-performance supercritical fluid chromatography and mass spectrometry is investigated with the aim to distinguish patients with breast, kidney, and prostate cancers from healthy controls. The mean sensitivity, specificity, and accuracy of the lipid profiling approach were 85%, 95%, and 92% for kidney cancer; 91%, 97%, and 94% for breast cancer; and 87%, 95%, and 92% for prostate cancer. No association of statistical models with tumor stage is observed. The statistically most significant lipid species for the differentiation of cancer types studied are CE 16:0, Cer 42:1, LPC 18:2, PC 36:2, PC 36:3, SM 32:1, and SM 41:1 These seven lipids represent a potential biomarker panel for kidney, breast, and prostate cancer screening, but a further verification step in a prospective study has to be performed to verify clinical utility.

• MeSH
• Early Detection of Cancer MeSH
• Adult MeSH
• Heparin chemistry   MeSH
• Mass Spectrometry MeSH
• Kidney metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Lipidomics * MeSH
• Lipids chemistry   MeSH
• Young Adult MeSH
• Biomarkers, Tumor metabolism   MeSH
• Prostatic Neoplasms metabolism   MeSH
• Breast Neoplasms metabolism   MeSH
• Area Under Curve MeSH
• Prospective Studies MeSH
• Prostate metabolism   MeSH
• Breast metabolism   MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Reproducibility of Results MeSH
• Retrospective Studies MeSH
• ROC Curve MeSH
• Aged MeSH
• Models, Statistical MeSH
• Case-Control Studies MeSH
• Chromatography, Supercritical Fluid MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Heparin MeSH
• Lipids MeSH
• Biomarkers, Tumor MeSH

Mass spectrometry raw data repositories, including Metabolomics Workbench and MetaboLights, have contributed to increased transparency in metabolomics studies and the discovery of novel insights in biology by reanalysis with updated computational metabolomics tools. Herein, we reanalyzed the previously published lipidomics data from nine algal species, resulting in the annotation of 1437 lipids achieving a 40% increase in annotation compared to the previous results. Specifically, diacylglyceryl-carboxyhydroxy-methylcholine (DGCC) in Pavlova lutheri and Pleurochrysis carterae, glucuronosyldiacylglycerol (GlcADG) in Euglena gracilis, and P. carterae, phosphatidylmethanol (PMeOH) in E. gracilis, and several oxidized phospholipids (oxidized phosphatidylcholine, OxPC; phosphatidylethanolamine, OxPE; phosphatidylglycerol, OxPG; phosphatidylinositol, OxPI) in Chlorella variabilis were newly characterized with the enriched lipid spectral databases. Moreover, we integrated the data from untargeted and targeted analyses from data independent tandem mass spectrometry (DIA-MS/MS) acquisition, specifically the sequential window acquisition of all theoretical fragment-ion MS/MS (SWATH-MS/MS) spectra, to increase the lipidomic annotation coverage. After the creation of a global library of precursor and diagnostic ions of lipids by the MS-DIAL untargeted analysis, the co-eluted DIA-MS/MS spectra were resolved in MRMPROBS targeted analysis by tracing the specific product ions involved in acyl chain compositions. Our results indicated that the metabolite quantifications based on DIA-MS/MS chromatograms were somewhat inferior to the MS1-centric quantifications, while the annotation coverage outperformed those of the untargeted analysis of the data dependent and DIA-MS/MS data. Consequently, integrated analyses of untargeted and targeted approaches are necessary to extract the maximum amount of metabolome information, and our results showcase the value of data repositories for the discovery of novel insights in lipid biology.

• Keywords
• computational metabolomics, data processing, data repository, lipidomics, reanalysis,
• Publication type
• Journal Article MeSH

Matrix-assisted laser desorption/ionization coupled with Orbitrap mass spectrometry (MALDI-Orbitrap-MS) is used for the clinical study of patients with renal cell carcinoma (RCC), as the most common type of kidney cancer. Significant changes in sulfoglycosphingolipid abundances between tumor and autologous normal kidney tissues are observed. First, sulfoglycosphingolipid species in studied RCC samples are identified using high mass accuracy full scan and tandem mass spectra. Subsequently, optimization, method validation, and statistical evaluation of MALDI-MS data for 158 tissues of 80 patients are discussed. More than 120 sulfoglycosphingolipids containing one to five hexosyl units are identified in human RCC samples based on the systematic study of their fragmentation behavior. Many of them are recorded here for the first time. Multivariate data analysis (MDA) methods, i.e., unsupervised principal component analysis (PCA) and supervised orthogonal partial least square discriminant analysis (OPLS-DA), are used for the visualization of differences between normal and tumor samples to reveal the most up- and downregulated lipids in tumor tissues. Obtained results are closely correlated with MALDI mass spectrometry imaging (MSI) and histologic staining. Important steps of the present MALDI-Orbitrap-MS approach are also discussed, such as the selection of best matrix, correct normalization, validation for semiquantitative study, and problems with possible isobaric interferences on closed masses in full scan mass spectra. Graphical Abstract ᅟ.

• Keywords
• MALDI, Orbitrap mass spectrometry, Renal cell carcinoma, Sulfatide, Sulfoglycosphingolipids,
• MeSH
• Principal Component Analysis MeSH
• Carcinoma, Renal Cell chemistry   diagnosis   pathology   MeSH
• Kidney chemistry   pathology   MeSH
• Humans MeSH
• Least-Squares Analysis MeSH
• Multivariate Analysis MeSH
• Biomarkers, Tumor analysis   MeSH
• Kidney Neoplasms chemistry   diagnosis   pathology   MeSH
• Sensitivity and Specificity MeSH
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods   MeSH
• Sulfoglycosphingolipids analysis   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Validation Study MeSH
• Names of Substances
• Biomarkers, Tumor MeSH
• Sulfoglycosphingolipids MeSH