Development of a polar lipid profiling method by supercritical fluid chromatography/mass spectrometry

Development of a high-throughput method for the comprehensive lipid analysis in milk using ultra-high performance supercritical fluid chromatography combined with quadrupole time-of-flight mass spectrometry

Milk lipids are one of the most complex materials in nature and are associated with many physiological functions, hence it is important to comprehensively characterize lipids profiles to evaluate the nutritional value of milk. A quick method was developed by ultra-high performance supercritical fluid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (UHPSFC-ESI-QTOF-MS) to analyze the non-polar and polar lipids profiles of cow, goat, buffalo, human milk, and infant formulas in 7 min. All chromatographic conditions were carefully optimized and their effect on the chromatographic behavior of lipid classes and species was discussed. Under optimized conditions, 12 lipid classes (triacylglycerols, diacylglycerols, monoglyceride, fatty acids, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol, sphingomyelin, lyso-phosphatidylcholine, and lyso-phosphatidylethanolamine) were separated and each class was further separated in single analysis to facilitate the identification. 250 lipid species in real samples were characterized and quantified. This result demonstrates the applicability of the UHPSFC-ESI-QTOF-MS method in the high-throughput and comprehensive lipid analysis of milk, and will hopefully help to provide nutritionists with the lipid distribution in different types of milk, as well as help in the design of more suitable infant formula for babies.

Effects of periostin deficiency on kidney aging and lipid metabolism

Periostin plays a crucial role in fibrosis, which is involved in kidney aging. A few studies have shown that lipid metabolism is involved in kidney aging. We investigated the role of periostin in lipid metabolism during kidney aging. Renal function, fibrosis, and inflammatory markers were studied using urine, blood, and tissue samples from wild-type (WT) C57BL/6 mice and Postn-null mice of 2 and 24 months of age. Lipids were quantitatively profiled using liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring mode. Renal function was worse and tubular atrophy/interstitial fibrosis, periostin expression, and inflammatory and fibrotic markers were more severe in aged WT mice than in young WT mice. In aged Postn-null mice, these changes were mitigated. Thirty-five differentially regulated lipids were identified. Phosphatidylcholines, cholesteryl ester, cholesterol, ceramide-1-phosphate, and CCL5 expression were significantly higher in aged WT mice than in aged Postn-null mice. Particularly, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid differed strongly between the two groups. Lysophosphatidylcholine acyltransferase 2, which converts lysophosphatidylcholine to phosphatidylcholine, was significantly higher in aged WT mice than in aged Postn-null mice. Periostin expression in the kidneys increased with age, and periostin ablation delayed aging. Changes in lipids and their metabolism were found in Postn-null mice. Further research on the precise mechanisms of and relationships between lipid expression and metabolism, kidney aging, and periostin expression is warranted.

A simple and rapid method to simultaneously analyze ciclesonide and its impurities in a ciclesonide metered-dose inhaler using on-line supercritical fluid extraction/supercritical fluid chromatography/quadrupole time-of-flight mass spectrometry

A simple and rapid on-line SFE/SFC/quadrupole TOF-MS method to simultaneously analyze active pharmaceutical ingredients and impurities from metered-dose inhalers (MDIs) was developed using ciclesonide MDI (CIC-MDI) as an example. CIC-MDI, as drug Alvesco®, has been approved for the treatment of bronchial asthma, and its major impurities are listed in the European Pharmacopoeia and in the supplementary package inserts of Alvesco® (called as "Pharmaceutical interview form" in Japan). In the developed method, CIC-MDI was manually sprayed only once on a glass disc prior to the SFE/SFC/quadrupole TOF-MS. In the SFE, CIC and its impurities and other impurities having various polarities and hydrophobicity, were extracted in 3.5 min and subsequently separated on a CHIRALPAK IE-3 column to be detected by quadrupole TOF-MS in 6.5 min. This method would be applicable to the analysis of other inhalable pharmaceutical products whose sample preparation requires complicated procedures, as well as to the analysis of general pharmaceutical products for profiling impurities.

Supercritical fluid chromatography coupled to mass spectrometry for lipidomics

Supercritical fluid chromatography (SFC) has experienced a particular revival in recent years thanks to the development of robust and efficient commercial systems. Because of its physico-chemical properties, supercritical carbon dioxide (CO₂ ) mixed with cosolvents and additives is particularly suitable for SFC to allow the elution of compounds of different polarities and more particularly complex lipids. Hyphenation with mass spectrometry (MS) is increasingly described in the literature but still requires many further developments in order to be as user-friendly as coupling with liquid chromatography. The basic concepts of SFC and MS hyphenation will be first considered. Then a representative example of method development in lipidomics will be introduced. In conclusion, the challenges and future needs in this field of research will be discussed.

Nuclear magnetic resonance-based serum metabolomic analysis reveals different disease evolution profiles between septic shock survivors and non-survivors

Background

Septic shock is the most severe phase of sepsis and is associated with high rates of mortality. However, early stage prediction of septic shock outcomes remains difficult. Metabolomic techniques have emerged as a promising tool for improving prognosis.

Methods

Orthogonal projections to latent structures-discriminant analysis (OPLS-DA) models separating the serum metabolomes of survivors from those of non-survivors were established with samples obtained at the intensive care unit (ICU) admission (H0) and 24 h later (H24). For 51 patients with available H0 and H24 samples, multi-level modeling was performed to provide insight into different metabolic evolutions that occurred between H0 and H24 in the surviving and non-surviving patients. Relative quantification and receiver operational characteristic curves (ROC) were applied to estimate the predictability of key discriminatory metabolites for septic shock mortality.

Results

Metabolites that were involved in energy supply and protein breakdown were primarily responsible for differentiating survivors from non-survivors. This was not only seen in the H0 and H24 discriminatory models, but also in the H0-H24 paired models. Reanalysis of extra H0-H24 paired samples in the established multi-level model demonstrated good performance of the model for the classification of samplings. According to the ROC results, nine discriminatory metabolites defined consistently from the unpaired model and the H0-H24 time-trend change (Δ_H24-H0) show good prediction of mortality. These results suggest that NMR-based metabolomic analysis is useful for a better overall assessment of septic shock patients.

Conclusions

Dysregulation of the metabolites identified by this study is associated with poor outcomes for septic shock. Evaluation of these compounds during the first 24 h after ICU admission in the septic shock patient may be helpful for estimating the severity of cases and for predicting outcomes.

Trial registration

All human serum samples were collected and stored, provided by the “center of biologic resources for liver disease”, in Jean Verdier Hospital, Bondy, France (BB-0033-00027).

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2456-z) contains supplementary material, which is available to authorized users.

Advances of supercritical fluid chromatography in lipid profiling

Supercritical fluid chromatography (SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the advances of SFC in targeted and untargeted lipid profiling. The advancement of the SFC instruments and the stationary phases are summarized. Typical applications of SFC to the targeted and untargeted lipid profiling are discussed in detail. Moreover, the perspectives of SFC in the lipid profiling are also proposed. As a useful and promising tool for investigating lipids in vitro and in vivo, SFC will predictably obtain further development.

Phospholipids as cancer biomarkers: Mass spectrometry-based analysis

Lipids, particularly phospholipids (PLs), are key components of cellular membrane. PLs play important and diverse roles in cells such as chemical-energy storage, cellular signaling, cell membranes, and cell-cell interactions in tissues. All these cellular processes are pertinent to cells that undergo transformation, cancer progression, and metastasis. Thus, there is a strong possibility that some classes of PLs are expected to present in cancer cells and tissues in cellular physiology. The mass spectrometric soft-ionization techniques, electrospray ionization (ESI), and matrix-assisted laser desorption/ionization (MALDI) are well-established in the proteomics field, have been used for lipidomic analysis in cancer research. This review focused on the applications of mass spectrometry (MS) mainly on ESI-MS and MALDI-MS in the structural characterization, molecular composition and key roles of various PLs present in cancer cells, tissues, blood, and urine, and on their importance for cancer-related problems as well as challenges for development of novel PL-based biomarkers. The profiling of PLs helps to rationalize their functions in biological systems, and will also provide diagnostic information to elucidate mechanisms behind the control of cancer, diabetes, and neurodegenerative diseases. The investigation of cellular PLs with MS methods suggests new insights on various cancer diseases and clinical applications in the drug discovery and development of biomarkers for various PL-related different cancer diseases. PL profiling in tissues, cells and body fluids also reflect the general condition of the whole organism and can indicate the existence of cancer and other diseases. PL profiling with MS opens new prospects to assess alterations of PLs in cancer, screening specific biomarkers and provide a basis for the development of novel therapeutic strategies. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:107-138, 2018.

A novel, fast and sensitive supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method for analysis of arachidonic acid metabolites

A validated method for rapid and reliable measurement of five arachidonic acid metabolites in biofluids using supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS).

Recent advances in lipid separations and structural elucidation using mass spectrometry combined with ion mobility spectrometry, ion-molecule reactions and fragmentation approaches

Lipids are a vital class of molecules that play important and varied roles in biological processes, however, fully understanding these roles is extremely difficult due to the immense number and diversity of possible lipid species. While recent advances in chromatography and high resolution mass spectrometry have greatly progressed knowledge about distinct lipid species and functions, effectively separating many lipids still remains problematic. Isomeric lipids have made lipid characterization especially difficult and occur due to subclasses having the same chemical composition, or species having multiple acyl chain connectivities (sn-1, sn-2, or sn-3), double bond positions and orientations (cis or trans), and functional group stereochemistries (R versus S). To aid in isomer characterization, ion mobility spectrometry separations, ion-molecule reactions and fragmentation techniques have increasingly been added to lipid analysis workflows. In this manuscript, we review the current state of these approaches and their capabilities for improving the identification of lipid species.

Supercritical fluid chromatography for lipid analysis in foodstuffs

The task of lipid analysis has always challenged separation scientists, and new techniques in chromatography were often developed for the separation of lipids; however, no single technique or methodology is yet capable of affording a comprehensive screening of all lipid species and classes. This review acquaints the role of supercritical fluid chromatography within the field of lipid analysis, from the early developed capillary separations based on pure CO₂ , to the most recent techniques employing packed columns under subcritical conditions, including the niche multidimensional techniques using supercritical fluids in at least one of the separation dimensions. A short history of supercritical fluid chromatography will be introduced first, from its early popularity in the late 1980s, to the sudden fall and oblivion until the last decade, experiencing a regain of interest within the chromatographic community. Afterwards, the subject of lipid nomenclature and classification will be briefly dealt with, before discussing the main applications of supercritical fluid chromatography for food analysis, according to the specific class of lipids.

Quantitative analysis of N-acylphosphatidylethanolamine molecular species in rat brain using solid-phase extraction combined with reversed-phase chromatography and tandem mass spectrometry

A novel method for the sensitive and selective identification and quantification of N‐acylphosphatidylethanolamine molecular species was developed. Samples were prepared using a combination of liquid–liquid and solid‐phase extraction, and intact N‐acylphosphatidylethanolamine species were determined by reversed‐phase high‐performance liquid chromatography coupled to positive electrospray tandem mass spectrometry. As a result of their biological functions as precursors for N‐acylethanolamines and as signaling molecules, tissue concentrations of N‐acylphosphatidylethanolamines are very low, and their analysis is additionally hindered by the vast excess of other sample components. Our sample preparation methods are able to selectively separate the analytes of interest from any expected biological interferences. Finally, the highest selectivity is achieved by coupling chromatographic separation and two N‐acyl chain specific selected reaction monitoring scans per analyte, enabling identification of both the N‐acyl chain and the phosphatidylethanolamine moiety. The validated method is suitable for the reliable quantification of N‐acylphosphatidylethanolamine species from rat brain with a lower limit of quantification of 10 pmol/g and a linear range up to 2300 pmol/g. In total, 41 N‐acylphosphatidylethanolamine molecular species with six different N‐acyl chains, amounting to a total concentration of 3 nmol/g, were quantified.

Lipidomics by Supercritical Fluid Chromatography

This review enlightens the role of supercritical fluid chromatography (SFC) in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC). It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering) or highly specific (mass spectrometry) detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides) defined by the LIPID MAPS consortium.

Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples

To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 μg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 μg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits.

Quantitation of phosphatidic acid and lysophosphatidic acid molecular species using hydrophilic interaction liquid chromatography coupled to electrospray ionization high resolution mass spectrometry

A method for a highly selective and sensitive identification and quantitation of lysophosphatidic acid (LPA) and phosphatidic acid (PA) molecular species was developed using hydrophilic interaction liquid chromatography (HILIC) followed by negative-ion electrospray ionization high resolution mass spectrometry. Different extraction methods for the polar LPA and PA species were compared and a modified Bligh & Dyer extraction by addition of 0.1M hydrochloric acid resulted in a ≈1.2-fold increase of recovery for the 7 PA and a more than 15-fold increase for the 6 LPA molecular species of a commercially available natural mix compared to conventional Bligh & Dyer extraction. This modified Bligh & Dyer extraction did not show any artifacts resulting from hydrolysis of natural abundant phospholipids. The developed HILIC method is able to separate all PA and LPA species from major polar membrane lipid classes which might have suppressive effects on the minor abundant lipid classes of interest. The elemental compositions of intact lipid species are provided by the high mass resolution of 100,000 and high mass accuracy below 3ppm of the Orbitrap instrument. Additionally, tandem mass spectra were generated in a parallel data dependent acquisition mode in the linear ion trap to provide structural information at molecular level. Limits of quantitation were identified at 45fmol on column and the dynamic range reaches 20pmol on column, covering the range of natural abundance well. By applying the developed method to mouse brain it can be shown that phosphatidic acid contains less unsaturated fatty acids with PA 34:1 and PA 36:1 as the major species. In contrast, for LPA species a high content of polyunsaturated fatty acids (LPA 20:4 and LPA 22:6) was quantified.

UPLC-MS-based serum metabonomics for identifying acute liver injury biomarkers in Chinese miniature pigs

Metabonomics has emerged as an important technology for exploring the underlying mechanisms of diseases and screening for biomarkers. In this investigation, to comprehensively assess metabolite changes in D-galactosamine (GalN)-induced liver injury in Chinese miniature pigs and to increase our understanding of physiological changes in normal and pathological states, we used ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to analyze metabolites and identify biomarkers in serum. Blood samples were collected both from 18 h after GalN treatment group and control group pigs. We performed multivariate analyses on the metabolite profiles to identify potential biomarkers of acute liver injury, which were then confirmed by tandem MS. Based on "variable of importance in the project" (VIP) values and S-plots, four groups of biomarkers were identified--namely conjugated bile acids, lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs) and fatty acid amides (FAAs)--that were present at significantly different levels in the control and GalN-induced groups. LPCs, PCs, and FAAs showed marked decreases in the GalN-treated group, whereas conjugated bile acids in the treated group showed considerable increases. Taken together, our results suggested that obvious metabolic disturbances occur during acute liver injury, which provided novel insights into the molecular mechanism(s) of D-galactosamine (GalN)-induced liver injury, and will facilitate future research and management of liver injury.

Metabolomics reveals trichloroacetate as a major contributor to trichloroethylene-induced metabolic alterations in mouse urine and serum

Trichloroethylene (TCE)-induced liver toxicity and carcinogenesis is believed to be mediated in part by activation of the peroxisome proliferator-activated receptor α (PPARα). However, the contribution of the two TCE metabolites, dichloroacetate (DCA) and trichloroacetate (TCA) to the toxicity of TCE, remains unclear. The aim of the present study was to determine the metabolite profiles in serum and urine upon exposure of mice to TCE, to aid in determining the metabolic response to TCE exposure and the contribution of DCA and TCA to TCE toxicity. C57BL/6 mice were administered TCE, TCA, or DCA, and urine and serum subjected to ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOFMS)-based global metabolomics analysis. The ions were identified through searching metabolomics databases and by comparison with authentic standards, and quantitated using multiple reactions monitoring. Quantitative polymerase chain reaction of mRNA, biochemical analysis, and liver histology were also performed. TCE exposure resulted in a decrease in urine of metabolites involved in fatty acid metabolism, resulting from altered expression of PPARα target genes. TCE treatment also induced altered phospholipid homeostasis in serum, as revealed by increased serum lysophosphatidylcholine 18:0 and 18:1, and phosphatidylcholine metabolites. TCA administration revealed similar metabolite profiles in urine and serum upon TCE exposure, which correlated with a more robust induction of PPARα target gene expression associated with TCA than DCA treatment. These data show the metabolic response to TCE exposure and demonstrate that TCA is the major contributor to TCE-induced metabolite alterations observed in urine and serum.

Simultaneous profiling of polar lipids by supercritical fluid chromatography/tandem mass spectrometry with methylation

Supercritical fluid chromatography/tandem mass spectrometry (SFC/MS/MS) with methylation was used for the simultaneous profiling of diverse polar lipids in a mixture. A high throughput, high resolution analysis of nineteen classes of polar lipids including phospholipids, lysophospholipids, and sphingolipids was performed in 6 min. Methylation by trimethylsilyl-diazomethane suppressed peak tailing and improved detection sensitivity of phosphatidylserine (PS), phosphatidic acid (PA), lysophosphatidylserine (LPS), lysophosphatidylinositol (LPI), lysophosphatidic acid (LPA), ceramide-1-phosphate (Cer1P), sphingosine-1-phosphate (So1P), and sphinganine-1-phosphate (Sa1P). The limits of detection for PS, PA, LPS, LPI, LPA, Cer1P, So1P, and Sa1P were enhanced 7.5-, 26.7-, 600-, 116.7-, 500-, 75-, 3000-, and 4500-fold, respectively. Global qualitative and quantitative analysis of not only the high-abundance species but also the low-abundance species in the polar lipids was achieved. When the method was applied to mouse liver, 4 PSs, 24 PAs, 3 lysophosphatidylethanolamines, 11 LPSs, 6 lysophosphatidylglycerols, 4 LPIs, 13 LPAs, 7 sphingomyelins, 11 Cer1Ps, So1P, and Sa1P were additionally analyzed. Furthermore, the quantification of various molecular species in each polar lipid was carried out.

Application of supercritical fluid carbon dioxide to the extraction and analysis of lipids

Supercritical carbon dioxide (SCCO2) is an ecofriendly supercritical fluid that is chemically inert, nontoxic, noninflammable and nonpolluting. As a green material, SCCO2 has desirable properties such as high density, low viscosity and high diffusivity that make it suitable for use as a solvent in supercritical fluid extraction, an effective and environment-friendly analytical method, and as a mobile phase for supercritical fluid chromatography, which facilitates high-throughput, high-resolution analysis. Furthermore, the low polarity of SCCO2 is suitable for the extraction and analysis of hydrophobic compounds. The growing concern surrounding environmental pollution has triggered the development of green analysis methods based on the use of SCCO2 in various laboratories and industries. SCCO2 is becoming an effective alternative to conventional organic solvents. In this review, the usefulness of SCCO2 in supercritical fluid extraction and supercritical fluid chromatography for the extraction and analysis of lipids is described.

Metabolic profiling of lipids by supercritical fluid chromatography/mass spectrometry

This review describes the usefulness of supercritical fluid chromatography (SFC) for the metabolic profiling of lipids. First, non-targeted lipid profiling by SFC/MS is described. The use of SFC/MS allows for high-throughput, exhaustive analysis of diverse lipids, and hence, this technique finds potential applications in lipidomics. Development of a polar lipid profiling method with trimethylsilyl (TMS) derivatization widens the scope of applicability of SFC/MS. SFC is a high-resolution technique that is suitable for non-targeted profiling aimed at the simultaneous analysis of many components. Next, targeted lipid profiling by SFC/MS is described. SFC is useful for the separation of lipids, such as carotenoids and triacylglycerols, which have numerous analogs with similar structures. In addition, SFC/MS shows the maximum efficiency for the target analysis of lipids in a biological sample that includes many matrices. Finally, a high-resolution, high-throughput analytical system based on SFC/MS is stated to be suitable for lipidomics because it is useful not only for the screening of lipid mixtures (as a fingerprint method) but also for the detailed profiling of individual components.