BACKGROUND: Reliable methods enabling detection of metal ions, and especially heavy metals, in different matrices are necessary in various fields such as ecology, pharmaceuticals and toxicology. As some of the currently used methods suffer from spectral and chemical interferences, this study investigates the applicability of SFC-MS/MS for the determination of metal ions. RESULTS: Effective novel approaches for metal ion analysis using CO2-based mobile phase were developed using three ligands forming metal complexes. As metal-EDTA complexes are prepared by simple addition of EDTA to the solution containing metal ions, this approach to metal ion analysis does not require laborious synthesis and isolation of solid metal-complexes. Besides, two other approaches using diethyldithiocarbamate and acetylacetonate as ligands were compared. Metal complexes of Cu, Co, Cr, Fe, Al, Mn, and Zn with all 3 ligands were synthesized and their identity was confirmed by high-resolution mass spectrometry (HRMS). The suitability of the three developed UHPSFC-MS/MS methods was examined using the determination of calibration range and repeatability of injections. Moreover, the universality of the developed UHPSFC-MS/MS method for the determination of metal-EDTA complexes was proved by analyzing Ni, Bi and Pb as additional metal ions. SIGNIFICANCE AND NOVELTY: This study demonstrates the extended range of applicability for SFC based separations. For the first time, the possibility to analyze metal complexes with EDTA using a fast and reliable ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) method is reported. The three developed UHPSFC-MS/MS methods are able to separate DDC, acac, and EDTA complexes of various metals very efficiently (total cycle times of 5, 2, and 3 min, respectively). They offer a fast and green alternative to chromatographic methods commonly used for metal ion analysis.
- Publication type
- Journal Article MeSH
Direct infusion of lipid extracts into the ion source of a mass spectrometer is a well-established method for lipid analysis. In most cases, nanofluidic devices are used for sample introduction. However, flow injection analysis (FIA) based on sample infusion from a chromatographic pump can offer a simple alternative to shotgun-based approaches. Here, we describe important modification of a method based on FIA and tandem mass spectrometry (MS/MS). We focus on minimizing contamination of the FIA/MS both to render the lipidomic platform more robust and to increase its capacity and applicability for long-sequence measurements required in clinical applications. Robust validation of the developed method confirms its suitability for lipid quantitation in human plasma analysis. Measurements of standard human plasma reference material (NIST SRM 1950) and a set of plasma samples collected from kidney cancer patients and from healthy volunteers yielded highly similar results between FIA-MS/MS and ultra-high-performance supercritical fluid chromatography (UHPSFC)/MS, thereby demonstrating that all modifications have practically no effect on the statistical output. Newly modified FIA-MS/MS allows for the quantitation of 141 lipid species in plasma (11 major lipid classes) within 5.7 min. Finally, we tested the method in a clinical laboratory of the General University Hospital in Prague. In the clinical setting, the method capacity reached 257 samples/day. We also show similar performance of the classification models trained based on the results obtained in clinical settings and the analytical laboratory at the University of Pardubice. Together, these findings demonstrate the high potential of the modified FIA-MS/MS for application in clinical laboratories to measure plasma and serum lipid profiles.
- MeSH
- Plasma chemistry MeSH
- Humans MeSH
- Lipidomics * methods MeSH
- Lipids analysis MeSH
- Flow Injection Analysis MeSH
- Tandem Mass Spectrometry * methods MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The applicability of ultrahigh-performance supercritical fluid chromatography coupled with mass spectrometry (UHPSFC/MS) for the qualitative analysis of metabolites with a wide polarity range (log P: -3.89-18.95) was evaluated using a representative set of 78 standards belonging to nucleosides, biogenic amines, carbohydrates, amino acids, and lipids. The effects of the gradient shape and the percentage of water (1, 2, and 5%) were investigated on the Viridis BEH column. The screening of eight stationary phases was performed for columns with different interaction sites, such as hydrogen bonding, hydrophobic, π-π, or anionic exchange type interactions. The highest number of compounds (67) of the set studied was detected on the Torus Diol column, which provided a resolution parameter of 39. The DEA column had the second best performance with 58 detected standards and the resolution parameter of 54. The overall performance of other parameters, such as selectivity, peak height, peak area, retention time stability, asymmetry factor, and mass accuracy, led to the selection of the Diol column for the final method. The comparison of additives showed that ammonium acetate gave a superior sensitivity over ammonium formate. Moreover, the influence of the ion source on the ionization efficiency was studied by employing atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI). The results proved the complementarity of both ionization techniques, but also the superior ionization capacity of the ESI source in the negative ion mode, for which 53% of the analytes were detected compared to only 7% for the APCI source. Finally, optimized analytical conditions were applied to the analysis of a pooled human plasma sample. 44 compounds from the preselected set were detected in human plasma using ESI-UHPSFC/MS in MSE mode considering both ionization modes.
- MeSH
- Amino Acids MeSH
- Atmospheric Pressure MeSH
- Chromatography, Liquid MeSH
- Mass Spectrometry MeSH
- Humans MeSH
- Chromatography, Supercritical Fluid * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Ultrahigh-performance supercritical fluid chromatography-mass spectrometry (UHPSFC/MS) has a great potential for the high-throughput lipidomic quantitation of biological samples; therefore, the full optimization and method validation of UHPSFC/MS is compared here with ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC/MS) in hydrophilic interaction liquid chromatography (HILIC) mode as the second powerful technique for the lipid class separation. First, the performance of six common extraction protocols is investigated, where the Folch procedure yields the best results with regard to recovery rate, matrix effect, and precision. Then, the full optimization and analytical validation for eight lipid classes using UHPSFC/MS and HILIC-UHPLC/MS methods are performed for the same sample set and applied for the lipidomic characterization of pooled samples of human plasma, human serum, and NIST SRM 1950 human plasma. The choice of appropriate internal standards (IS) for individual lipid classes has a key importance for reliable quantitative workflows illustrated by the selectivity while validation and the calculation of the quantitation error using multiple internal standards per lipid class. Validation results confirm the applicability of both methods, but UHPSFC/MS provides some distinct advantages, such as the successful separation of both non-polar and polar lipid classes unlike to HILIC-UHPLC/MS, shorter total run times (8 vs. 10.5 min), and slightly higher robustness. Various types of correlations between methods (UHPSFC/MS and HILIC-UHPLC/MS), biological material (plasma and serum), IS (laboratory and commercially mixtures), and literature data on the standard reference material show the intra- and inter-laboratory comparison in the quantitation of lipid species from eight lipid classes, the concentration differences in serum and plasma as well as the applicability of non-commercially available internal standard mixtures for lipid quantitation.
- MeSH
- Mass Spectrometry methods MeSH
- Plasma chemistry MeSH
- Humans MeSH
- Lipidomics methods MeSH
- Lipids blood chemistry MeSH
- Serum chemistry MeSH
- Chromatography, Supercritical Fluid methods MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Validation Study MeSH
Ultrahigh-performance supercritical fluid chromatography - mass spectrometry (UHPSFC/MS), ultrahigh-performance liquid chromatography - mass spectrometry (UHPLC/MS), and matrix-assisted laser desorption/ionization (MALDI) - MS techniques were used for the lipidomic characterization of exosomes isolated from human plasma. The high-throughput methods UHPSFC/MS and UHPLC/MS using a silica-based column containing sub-2 μm particles enabled the lipid class separation and the quantitation based on exogenous class internal standards in <7 minute run time. MALDI provided the complementary information on anionic lipid classes, such as sulfatides. The nontargeted analysis of 12 healthy volunteers was performed, and absolute molar concentration of 244 lipids in exosomes and 191 lipids in plasma belonging to 10 lipid classes were quantified. The statistical evaluation of data included principal component analysis, orthogonal partial least square discriminant analysis, S-plots, p-values, T-values, fold changes, false discovery rate, box plots, and correlation plots, which resulted in the information on lipid changes in exosomes in comparison to plasma. The major changes were detected in the composition of triacylglycerols, diacylglycerols, phosphatidylcholines, and lysophosphatidylcholines, whereby sphingomyelins, phosphatidylinositols, and sulfatides showed rather similar profiles in both biological matrices.
- MeSH
- Diglycerides blood isolation & purification metabolism MeSH
- Adult MeSH
- Exosomes chemistry metabolism MeSH
- Phosphatidylcholines blood isolation & purification metabolism MeSH
- Middle Aged MeSH
- Humans MeSH
- Lipidomics methods MeSH
- Lysophosphatidylcholines blood isolation & purification metabolism MeSH
- Lipid Metabolism * MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods MeSH
- Chromatography, Supercritical Fluid methods MeSH
- Triglycerides blood isolation & purification metabolism MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Healthy Volunteers MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
This new analytical approach for high-throughput and comprehensive lipidomic analysis of biological samples using ultrahigh-performance supercritical fluid chromatography (UHPSFC) with electrospray ionization-mass spectrometry (ESI-MS) is based on lipid class separation using 1.7 μm particle bridged ethylene hybrid silica columns and a gradient of methanol-water-ammonium acetate mixture as a modifier. The method enables a fast separation of 30 nonpolar and polar lipid classes within 6-min analysis time covering six main lipid categories including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, and prenols. Individual lipid species within lipid classes are identified based on positive- and negative-ion full scan and tandem mass spectra measured with high mass accuracy and high resolving power. The method is used for the quantitative analysis of lipid species in biological tissues using internal standards for each lipid class. This high-throughput, comprehensive, and accurate UHPSFC/ESI-MS method is suitable for the lipidomic analysis of large sample sets in clinical research.
- MeSH
- Glycerophospholipids analysis MeSH
- Spectrometry, Mass, Electrospray Ionization methods MeSH
- Lipids analysis MeSH
- Metabolomics methods MeSH
- Pentanols analysis MeSH
- Sphingolipids analysis MeSH
- Sterols analysis MeSH
- Chromatography, Supercritical Fluid methods MeSH
- Tandem Mass Spectrometry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Lipidomic analysis of biological samples in a clinical research represents challenging task for analytical methods given by the large number of samples and their extreme complexity. In this work, we compare direct infusion (DI) and chromatography - mass spectrometry (MS) lipidomic approaches represented by three analytical methods in terms of comprehensiveness, sample throughput, and validation results for the lipidomic analysis of biological samples represented by tumor tissue, surrounding normal tissue, plasma, and erythrocytes of kidney cancer patients. Methods are compared in one laboratory using the identical analytical protocol to ensure comparable conditions. Ultrahigh-performance liquid chromatography/MS (UHPLC/MS) method in hydrophilic interaction liquid chromatography mode and DI-MS method are used for this comparison as the most widely used methods for the lipidomic analysis together with ultrahigh-performance supercritical fluid chromatography/MS (UHPSFC/MS) method showing promising results in metabolomics analyses. The nontargeted analysis of pooled samples is performed using all tested methods and 610 lipid species within 23 lipid classes are identified. DI method provides the most comprehensive results due to identification of some polar lipid classes, which are not identified by UHPLC and UHPSFC methods. On the other hand, UHPSFC method provides an excellent sensitivity for less polar lipid classes and the highest sample throughput within 10min method time. The sample consumption of DI method is 125 times higher than for other methods, while only 40μL of organic solvent is used for one sample analysis compared to 3.5mL and 4.9mL in case of UHPLC and UHPSFC methods, respectively. Methods are validated for the quantitative lipidomic analysis of plasma samples with one internal standard for each lipid class. Results show applicability of all tested methods for the lipidomic analysis of biological samples depending on the analysis requirements.
The potential of ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC/MS) and ultrahigh-performance supercritical fluid chromatography (UHPSFC) coupled to negative-ion electrospray ionization mass spectrometry (ESI-MS) for the analysis of 46 oxylipins and 2 fatty acid standards is compared in terms of their chromatographic resolution with the emphasis on distinguishing isobaric interferences and the method sensitivity. UHPLC provides the baseline separation of 24 isobaric oxylipins within 13min, while UHPSFC enables the separation of only 20 isobaric oxylipins within 8min. Moreover, the UHPLC/ESI-MS method provides an average improvement of sensitivity by 3.5-fold. A similar trend is observed in the analysis of human plasma samples, but lower ion suppression effects caused by lysophospholipids (LPL) are observed in case of UHPSFC/ESI-MS due to better separation of LPL. Both methods are fully applicable for the analysis of oxylipins, but UHPLC/ESI-MS method is preferred due to better separation and higher sensitivity, which results in the identification of 31 oxylipins in human plasma based on available standards and additional tentative 20 identifications based on accurate m/z values and the fragmentation behavior known from the literature.
- MeSH
- Spectrometry, Mass, Electrospray Ionization methods MeSH
- Humans MeSH
- Oxylipins blood chemistry MeSH
- Solvents chemistry MeSH
- Chromatography, Supercritical Fluid methods MeSH
- Temperature MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents.
- MeSH
- Anabolic Agents urine MeSH
- Chromatography, Gas MeSH
- Doping in Sports prevention & control MeSH
- Liquid-Liquid Extraction MeSH
- Humans MeSH
- Substance Abuse Detection methods MeSH
- Steroids urine 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
