Reversed-phase ultrahigh-performance liquid chromatography-mass spectrometry (RP-UHPLC/MS) method is optimized for the quantitation of a large number of lipid species in biological samples, primarily in human plasma and serum. The method uses a C18 bridged ethylene hybrid (BEH) column (150 × 2.1 mm; 1.7 μm) for the separation of lipids from 23 subclasses with a total run time of 25 min. Lipid species separation allows the resolution of isobaric and isomeric lipid forms. A triple quadrupole mass spectrometer is used for targeted lipidomic analysis using multiple reaction monitoring (MRM) in the positive ion mode. Data are evaluated by Skyline software, and the concentrations of analytes are determined using internal standards per each individual lipid class.

• Keywords
• High-throughput lipidomics, Mass spectrometry, Plasma, Quantitation, Reversed-phase, Serum, Ultrahigh-performance liquid chromatography,
• MeSH
• Chromatography, Reverse-Phase * methods   MeSH
• Mass Spectrometry methods   MeSH
• Liquid Chromatography-Mass Spectrometry MeSH
• Humans MeSH
• Lipidomics * methods   MeSH
• Lipids * analysis   MeSH
• High-Throughput Screening Assays methods   MeSH
• Software MeSH
• Tandem Mass Spectrometry methods   MeSH
• Chromatography, High Pressure Liquid methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Lipids * MeSH

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

The ever-increasing use of chemicals and the rising incidence of adverse reproductive effects in the modern environment have become an emerging concern. Several studies have shown that environmental contaminants, such as organophosphate flame retardants (OPFRs), negatively impact reproductive health. To evaluate the potential endocrine-related adverse reproductive effects of widely used and priority-listed compound 2-Ethylhexyl diphenyl phosphate (EHDPP), we characterized its effects on adrenal steroidogenesis in human adrenocortical (H295R) cells. The cells were exposed to EHDPP (1 and 5 μM) for 48 h, and the production of hormones, including progesterone, androstenedione, testosterone, estradiol, cortisol, and aldosterone, was measured. In addition, LC-MS/MS-based lipidomics analysis was done to quantify intracellular lipid profiles, and transcriptional assays were performed to examine the expression of genes related to corticosteroidogenesis, lipid metabolism, and mitochondrial dynamics. Our findings indicate that EHDPP disrupts hormone regulation in vitro, as evidenced by increased estradiol, cortisol, and aldosterone secretion. The expression of key corticosteroidogenic genes (CYP11B2, CYP21A1, 3β-HSD2, and 17β-HSD1) was upregulated significantly upon EHDPP exposure. Intracellular lipidomics revealed EHDPP-mediated disruption, including reduced total cholesterol ester, sphingolipids, and increased phospholipids, triglyceride species, and saturated-monounsaturated lipids subspecies. These alterations were accompanied by decreased ACAT2 and SCD1 gene expression. Moreover, a shift in mitochondrial dynamics was indicated by increased MF1 expression and decreased FIS1 expression. These data suggest that EHDPP disrupts adrenal steroidogenesis and lipid homeostasis, emphasizing its potential endocrine-disrupting effects.

• MeSH
• Humans MeSH
• Lipidomics MeSH
• Lipid Metabolism * drug effects   MeSH
• Adrenal Glands * drug effects   metabolism   cytology   MeSH
• Organophosphates * pharmacology   MeSH
• Steroids * biosynthesis   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Organophosphates * MeSH
• Steroids * MeSH

Chemical derivatization involves the reaction of an analyte with a derivatization agent to modify its structure, improving the peak shape, chromatographic performance, structural analysis, ionization efficiency, and sensitivity. A novel derivatization method using 3-(chlorosulfonyl)benzoic acid is developed for the determination of monoacylglycerols, diacylglycerols, free sterols, and tocopherols using the reversed-phase ultra-high-performance liquid chromatography-tandem mass spectrometry (RP-UHPLC/MS/MS) method in the negative ion mode. The chromatographic and mass spectrometric properties of derivatized lipids are investigated by using 29 lipid standards spanning four lipid classes. The derivatization process is optimized using pooled plasma spiked by 9 internal standards, achieving an optimal yield with a reaction time of 40 min at 60 °C. The stability of the derivatives is confirmed, with short-term stability maintained for 10 h at 4 °C and long-term stability preserved for 5 days at -80 °C. The repeatability and reproducibility are verified by one/two operator(s), which underscores the simplicity and robustness of the method, and calibration curves with high linear regression coefficients illustrate the accuracy of the method. The derivatization approach, which combines RP-UHPLC/MS/MS and the use of specific fragmentation patterns, significantly reduces limits of detection, reaching 15-25 pmol/mL for free sterols in plasma. The optimized method is applied to the analysis of human plasma, leading to the identification of 92 lipid species in the targeted lipid classes. This represents a substantial improvement in sensitivity and detection capabilities compared to those of previously reported methods.

• MeSH
• Chromatography, Reverse-Phase methods   MeSH
• Humans MeSH
• Sterols * blood   analysis   MeSH
• Tandem Mass Spectrometry * methods   MeSH
• Chromatography, High Pressure Liquid methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Sterols * MeSH

Multidimensional chromatography offers enhanced chromatographic resolution and peak capacity, which are crucial for analyzing complex samples. This study presents a novel comprehensive online multidimensional chromatography method for the lipidomic analysis of biological samples, combining lipid class and lipid species separation approaches. The method combines optimized reversed-phase ultrahigh-performance liquid chromatography (RP-UHPLC) in the first dimension, utilizing a 150 mm long C18 column, with ultrahigh-performance supercritical fluid chromatography (UHPSFC) in the second dimension, using a 10 mm long silica column, both with sub-2 μm particles. A key advantage of employing UHPSFC in the second dimension is its ability to perform ultrafast analysis using gradient elution with a sampling time of 0.55 min. This approach offers a significant increase in the peak capacity. Compared to our routinely used 1D methods, the peak capacity of the 4D system is 10 times higher than RP-UHPLC and 18 times higher than UHPSFC. The entire chromatographic system is coupled with a high-resolution quadrupole-time-of-flight (QTOF) mass analyzer using electrospray ionization (ESI) in both full-scan and tandem mass spectrometry (MS/MS) and with positive- and negative-ion polarities, enabling the detailed characterization of the lipidome. The confident identification of lipid species is achieved through characteristic ions in both polarity modes, information from MS elevated energy (MSE) and fast data-dependent analysis scans, and mass accuracy below 5 ppm. This analytical method has been used to characterize the lipidomic profile of the total lipid extract from human plasma, which has led to the identification of 298 lipid species from 16 lipid subclasses.

• MeSH
• Humans MeSH
• Lipidomics * methods   MeSH
• Lipids * analysis   MeSH
• Chromatography, Supercritical Fluid methods   MeSH
• Tandem Mass Spectrometry * methods   MeSH
• Chromatography, High Pressure Liquid methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Lipids * MeSH

The rapid increase in lipidomic studies has led to a collaborative effort within the community to establish standards and criteria for producing, documenting, and disseminating data. Creating a dynamic easy-to-use checklist that condenses key information about lipidomic experiments into common terminology will enhance the field's consistency, comparability, and repeatability. Here, we describe the structure and rationale of the established Lipidomics Minimal Reporting Checklist to increase transparency in lipidomics research.

• Keywords
• FAIR, checklist, lipid metabolism, lipidomics, mass spectrometry, metabolomics, quality control, reference standards,
• MeSH
• Checklist * MeSH
• Humans MeSH
• Lipidomics * methods   standards   MeSH
• Lipids analysis   chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Lipids MeSH

Microflow liquid chromatography interfaced with mass spectrometry (μLC-MS/MS) is increasingly applied for high-throughput profiling of biological samples and has been proven to have an acceptable trade-off between sensitivity and reproducibility. However, lipidomics applications are scarce. We optimized a μLC-MS/MS system utilizing a 1 mm inner diameter × 100 mm column coupled to a triple quadrupole mass spectrometer to establish a sensitive, high-throughput, and robust single-shot lipidomics workflow. Compared to conventional lipidomics methods, we achieve a ∼4-fold increase in response, facilitating quantification of 351 lipid species from a single iPSC-derived cerebral organoid during a 15 min LC-MS analysis. Consecutively, we injected 303 samples over ∼75 h to prove the robustness and reproducibility of the microflow separation. As a proof of concept, μLC-MS/MS analysis of Alzheimer's disease patient-derived iPSC cerebral organoid reveals differential lipid metabolism depending on APOE phenotype (E3/3 vs E4/4). Microflow separation proves to be an environmentally friendly and cost-effective method as it reduces the consumption of harmful solvents. Also, the data demonstrate robust, in-depth, high-throughput performance to enable routine clinical or biomedical applications.

• MeSH
• Apolipoproteins E MeSH
• Chromatography, Liquid methods   MeSH
• Phenotype MeSH
• Liquid Chromatography-Mass Spectrometry * MeSH
• Humans MeSH
• Lipidomics MeSH
• Reproducibility of Results MeSH
• Tandem Mass Spectrometry * methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Apolipoproteins E 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