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Engel KM, Prabutzki P, Leopold J, Nimptsch A, Lemmnitzer K, Vos DRN, Hopf C, Schiller J. A new update of MALDI-TOF mass spectrometry in lipid research. Prog Lipid Res 2022; 86:101145. [PMID: 34995672 DOI: 10.1016/j.plipres.2021.101145] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/06/2021] [Accepted: 12/29/2021] [Indexed: 01/06/2023]
Abstract
Matrix-assisted laser desorption and ionization (MALDI) mass spectrometry (MS) is an indispensable tool in modern lipid research since it is fast, sensitive, tolerates sample impurities and provides spectra without major analyte fragmentation. We will discuss some methodological aspects, the related ion-forming processes and the MALDI MS characteristics of the different lipid classes (with the focus on glycerophospholipids) and the progress, which was achieved during the last ten years. Particular attention will be given to quantitative aspects of MALDI MS since this is widely considered as the most serious drawback of the method. Although the detailed role of the matrix is not yet completely understood, it will be explicitly shown that the careful choice of the matrix is crucial (besides the careful evaluation of the positive and negative ion mass spectra) in order to be able to detect all lipid classes of interest. Two developments will be highlighted: spatially resolved Imaging MS is nowadays well established and the distribution of lipids in tissues merits increasing interest because lipids are readily detectable and represent ubiquitous compounds. It will also be shown that a combination of MALDI MS with thin-layer chromatography (TLC) enables a fast spatially resolved screening of an entire TLC plate which makes the method competitive with LC/MS.
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Affiliation(s)
- Kathrin M Engel
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Patricia Prabutzki
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Jenny Leopold
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Ariane Nimptsch
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - Katharina Lemmnitzer
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany
| | - D R Naomi Vos
- Center for Biomedical Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Paul-Wittsack-Strasse 10, D-68163 Mannheim, Germany
| | - Carsten Hopf
- Center for Biomedical Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Paul-Wittsack-Strasse 10, D-68163 Mannheim, Germany
| | - Jürgen Schiller
- Leipzig University, Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstraße 16-18, D-04107, Germany.
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2
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Borisov RS, Matveeva MD, Zaikin VG. Reactive Matrices for Analytical Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry. Crit Rev Anal Chem 2021; 53:1027-1043. [PMID: 34969337 DOI: 10.1080/10408347.2021.2001309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
In recent years, a special focus is placed on the usage of reactive matrices for analytical matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). Since 2003, when the term "reactive matrices" was suggested and the dignity of compounds, possessing dualistic properties as matrices and derivatization agents was demonstrated, corresponding approach has found application in various fields and, in particular, in bioanalysis (metabolomics, lipidomics, etc.). The main advantage of this methodology is that it reduces sample treatment time, simplifies the procedure of sample handling, improves the sensitivity of analysis, enhances the molecular identification and profiling. Within the framework of this review, the main attention is paid to "true" reactive matrices that interact with analyte molecules through an exchange or addition reactions. A special section discusses practical application of reactive matrices in the determination of the distribution of targeted and non-targeted organic substances on the surface of biological tissue sections by MALDI-MS imaging. In this critical review, a controversial proposal is made to consider protonating and deprotonating matrices as reactive, because they can undergo a chemical reaction such as proton transfer that occurs in both target solution and MALDI plume. In this respect, special attention is paid to "proton sponge" matrices that have found a wide application in the analysis of various acidic compounds by MALDI-MS in the negative mode. Historical data on the formation of ions and the fate of matrices in MALDI are considered at the beginning of this article.
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Affiliation(s)
- Roman S Borisov
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russian Federation
| | - Mariya D Matveeva
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russian Federation
| | - Vladimir G Zaikin
- A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russian Federation
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3
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Podolskaya EP, Gladchuk AS, Keltsieva OA, Dubakova PS, Silyavka ES, Lukasheva E, Zhukov V, Lapina N, Makhmadalieva MR, Gzgzyan AM, Sukhodolov NG, Krasnov KA, Selyutin AA, Frolov A. Thin Film Chemical Deposition Techniques as a Tool for Fingerprinting of Free Fatty Acids by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. Anal Chem 2018; 91:1636-1643. [PMID: 30532949 DOI: 10.1021/acs.analchem.8b05296] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metabolic fingerprinting is a powerful analytical technique, giving access to high-throughput identification and relative quantification of multiple metabolites. Because of short analysis times, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is the preferred instrumental platform for fingerprinting, although its power in analysis of free fatty acids (FFAs) is limited. However, these metabolites are the biomarkers of human pathologies and indicators of food quality. Hence, a high-throughput method for their fingerprinting is required. Therefore, here we propose a MALDI-TOF-MS method for identification and relative quantification of FFAs in biological samples of different origins. Our approach relies on formation of monomolecular Langmuir films (LFs) at the interphase of aqueous barium acetate solution, supplemented with low amounts of 2,5-dihydroxybenzoic acid, and hexane extracts of biological samples. This resulted in detection limits of 10-13-10-14 mol and overall method linear dynamic range of at least 4 orders of magnitude with accuracy and precision within 2 and 17%, respectively. The method precision was verified with eight sample series of different taxonomies, which indicates a universal applicability of our approach. Thereby, 31 and 22 FFA signals were annotated by exact mass and identified by tandem MS, respectively. Among 20 FFAs identified in Fucus algae, 14 could be confirmed by gas chromatography-mass spectrometry.
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Affiliation(s)
- Ekaterina P Podolskaya
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019.,Institute of Analytical Instrumentation , Russian Academy of Sciences , St. Petersburg , Russia 198095
| | - Alexey S Gladchuk
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019.,Peter the Great St. Petersburg Polytechnic University , St. Petersburg , Russia 195251
| | - Olga A Keltsieva
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019.,Institute of Analytical Instrumentation , Russian Academy of Sciences , St. Petersburg , Russia 198095
| | - Polina S Dubakova
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019.,Peter the Great St. Petersburg Polytechnic University , St. Petersburg , Russia 195251
| | | | | | - Vladimir Zhukov
- All-Russia Research Institute for Agricultural Microbiology , St. Petersburg , Russia 196608
| | - Natalia Lapina
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019
| | - Manizha R Makhmadalieva
- Research Institute of Obstetrics, Gynecology and Reproductology named after D.O. Ott , St. Petersburg , Russia 199034
| | - Alexander M Gzgzyan
- Research Institute of Obstetrics, Gynecology and Reproductology named after D.O. Ott , St. Petersburg , Russia 199034
| | - Nikolai G Sukhodolov
- Institute of Analytical Instrumentation , Russian Academy of Sciences , St. Petersburg , Russia 198095
| | - Konstantin A Krasnov
- Institute of Toxicology , Federal Medical-Biological Agency of Russia , St. Petersburg , Russia 192019
| | | | - Andrej Frolov
- Department of Bioorganic Chemistry , Leibniz Institute of Plant Biochemistry , Halle/Saale , Germany 06120
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Leopold J, Popkova Y, Engel KM, Schiller J. Recent Developments of Useful MALDI Matrices for the Mass Spectrometric Characterization of Lipids. Biomolecules 2018; 8:biom8040173. [PMID: 30551655 PMCID: PMC6316665 DOI: 10.3390/biom8040173] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/06/2018] [Accepted: 12/10/2018] [Indexed: 12/24/2022] Open
Abstract
Matrix-assisted laser desorption/ionization (MALDI) is one of the most successful “soft” ionization methods in the field of mass spectrometry and enables the analysis of a broad range of molecules, including lipids. Although the details of the ionization process are still unknown, the importance of the matrix is commonly accepted. Both, the development of and the search for useful matrices was, and still is, an empirical process, since properties like vacuum stability, high absorption at the laser wavelength, etc. have to be fulfilled by a compound to become a useful matrix. This review provides a survey of successfully used MALDI matrices for the lipid analyses of complex biological samples. The advantages and drawbacks of the established organic matrix molecules (cinnamic or benzoic acid derivatives), liquid crystalline matrices, and mixtures of common matrices will be discussed. Furthermore, we will deal with nanocrystalline matrices, which are most suitable to analyze small molecules, such as free fatty acids. It will be shown that the analysis of mixtures and the quantitative analysis of small molecules can be easily performed if the matrix is carefully selected. Finally, some basic principles of how useful matrix compounds can be “designed” de novo will be introduced.
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Affiliation(s)
- Jenny Leopold
- Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstr. 16/18, Leipzig University, D-04107 Leipzig, Germany.
| | - Yulia Popkova
- Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstr. 16/18, Leipzig University, D-04107 Leipzig, Germany.
| | - Kathrin M Engel
- Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstr. 16/18, Leipzig University, D-04107 Leipzig, Germany.
| | - Jürgen Schiller
- Faculty of Medicine, Institute for Medical Physics and Biophysics, Härtelstr. 16/18, Leipzig University, D-04107 Leipzig, Germany.
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Leopold J, Popkova Y, Engel KM, Schiller J. Visualizing phosphatidylcholine via mass spectrometry imaging: relevance to human health. Expert Rev Proteomics 2018; 15:791-800. [PMID: 30241449 DOI: 10.1080/14789450.2018.1526679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Mass spectrometry imaging (MSI) techniques are nowadays widely used to obtain spatially resolved metabolite information from biological tissues. Since (phospho)lipids occur in all animal tissues and are very sensitively detectable, they are often in the focus of such studies. This particularly applies for phosphatidylcholines (PC) which are very sensitively detectable as positive ions due to the permanent positive charge of their choline headgroup. Areas covered: After a short introduction of lipid species occurring in biological systems and approaches normally used to obtain spatially resolved mass spectra (with the focus on matrix-assisted laser desorption/ionization coupled to time-of-flight (MALDI-TOF) MSI) a survey will be given which diseases have so far been characterized by changes of the PC composition. Expert commentary: Since PC species are very sensitively detectable by MS, sensitivity is not a major issue. However, spatial resolution is still limited and cellular dimensions can be hardly resolved by MALDI-TOF MSI, which is a critical point of the available approaches. Due to lacks of reproducibility and standardization further development is required.
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Affiliation(s)
- Jenny Leopold
- a Faculty of Medicine, Institute for Medical Physics and Biophysics , Leipzig University , Leipzig , Germany
| | - Yulia Popkova
- a Faculty of Medicine, Institute for Medical Physics and Biophysics , Leipzig University , Leipzig , Germany
| | - Kathrin M Engel
- a Faculty of Medicine, Institute for Medical Physics and Biophysics , Leipzig University , Leipzig , Germany
| | - Jürgen Schiller
- a Faculty of Medicine, Institute for Medical Physics and Biophysics , Leipzig University , Leipzig , Germany
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Hansen RL, Lee YJ. High-Spatial Resolution Mass Spectrometry Imaging: Toward Single Cell Metabolomics in Plant Tissues. CHEM REC 2017; 18:65-77. [PMID: 28685965 DOI: 10.1002/tcr.201700027] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Indexed: 12/27/2022]
Abstract
Mass spectrometry imaging (MSI) is a powerful tool that has advanced our understanding of complex biological processes by enabling unprecedented details of metabolic biology to be uncovered. Through the use of high-spatial resolution MSI, metabolite localizations can be obtained with high precision. Here we describe our recent progress to enhance the spatial resolution of matrix-assisted laser desorption/ionization (MALDI) MSI from ∼50 μm with the commercial configuration to ∼5 μm. Additionally, we describe our efforts to develop a 'multiplex MSI' data acquisition method to allow more chemical information to be obtained on a single tissue in a single instrument run, and the development of new matrices to improve the ionization efficiency for a variety of small molecule metabolites. In combination, these contributions, along with the efforts of others, will bring MSI experiments closer to achieving metabolomic scale.
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Affiliation(s)
- Rebecca L Hansen
- Department of Chemistry, Iowa State University, 35 A Roy J Carver Co-Lab, 1111 WOI Road Ames, IA 50011, United States of America
| | - Young Jin Lee
- Department of Chemistry, Iowa State University, 35 A Roy J Carver Co-Lab, 1111 WOI Road Ames, IA 50011, United States of America
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Stelzner K, Herbert D, Popkova Y, Lorz A, Schiller J, Gericke M, Klöting N, Blüher M, Franz S, Simon JC, Saalbach A. Free fatty acids sensitize dendritic cells to amplify TH1/TH17-immune responses. Eur J Immunol 2016; 46:2043-53. [PMID: 27214608 DOI: 10.1002/eji.201546263] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 04/25/2016] [Accepted: 05/18/2016] [Indexed: 12/20/2022]
Abstract
Obesity is associated with body fat gain and impaired glucose metabolism. Here, we identified both body fat gain in obesity and impaired glucose metabolism as two independent risk factors for increased serum levels of free fatty acids (FFAs). Since obesity is associated with increased and/or delayed resolution of inflammation observed in various chronic inflammatory diseases such as psoriasis, we investigated the impact of FFAs on human monocyte-derived and mouse bone marrow-derived dendritic cell (DCs) functions relevant for the pathogenesis of chronic inflammation. FFAs such as palmitic acid (PA) and oleic acid (OA) did not affect the pro-inflammatory immune response of DCs. In contrast, PA and OA sensitize DCs resulting in augmented secretion of TH1/TH17-instructive cytokines upon pro-inflammatory stimulation. Interestingly, obesity in mice worsened a TH1/TH17-driven psoriasis-like skin inflammation. Strong correlation of the amount of total FFA, PA, and OA in serum with the severity of skin inflammation points to a critical role of FFA in obesity-mediated exacerbation of skin inflammation. Our data suggest that increased levels of FFAs might be a predisposing factor promoting a TH1/TH17-mediated inflammation such as psoriasis in response to an inflammatory danger signal.
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Affiliation(s)
- Kristin Stelzner
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
| | - Diana Herbert
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
| | - Yulia Popkova
- Institute of Medical Physics and Biophysics, Medical Faculty of University of Leipzig, Germany
| | - Axel Lorz
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
| | - Jürgen Schiller
- Institute of Medical Physics and Biophysics, Medical Faculty of University of Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy, Medical Faculty of University of Leipzig, Germany
| | - Nora Klöting
- IFB Adiposity Diseases, University of Leipzig, Germany
| | - Matthias Blüher
- Department of Medicine, Medical Faculty of University of Leipzig, Germany
| | - Sandra Franz
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
| | - Jan C Simon
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
| | - Anja Saalbach
- Department of Dermatology, Venerology and Allergology, Medical Faculty of University of Leipzig, Germany
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Unexpected products of the hypochlorous acid-induced oxidation of oleic acid: A study using high performance thin-layer chromatographyelectrospray ionization mass spectrometry. J Chromatogr A 2016; 1439:89-96. [DOI: 10.1016/j.chroma.2015.11.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/08/2015] [Accepted: 11/17/2015] [Indexed: 01/14/2023]
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9
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Weißflog J, Svatoš A. 1,8-Di(piperidinyl)-naphthalene – rationally designed MAILD/MALDI matrix for metabolomics and imaging mass spectrometry. RSC Adv 2016. [DOI: 10.1039/c6ra17237g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of small molecules requires special matrices, which do not generate interfering signals below m/z 500.
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Affiliation(s)
- Jerrit Weißflog
- Mass Spectrometry/Proteomics Research Group Max Planck Institute for Chemical Ecology
- 07745 Jena
- Germany
| | - Aleš Svatoš
- Mass Spectrometry/Proteomics Research Group Max Planck Institute for Chemical Ecology
- 07745 Jena
- Germany
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Pirkl A, Meier M, Popkova Y, Letzel M, Schnapp A, Schiller J, Dreisewerd K. Analysis of free fatty acids by ultraviolet laser desorption ionization mass spectrometry using insect wings as hydrophobic sample substrates. Anal Chem 2014; 86:10763-71. [PMID: 25268473 DOI: 10.1021/ac5020047] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Physiologically relevant free fatty acids (FFAs) were analyzed by UV-laser desorption/ionization orthogonal extracting time-of-flight mass spectrometry (LDI-oTOF-MS). Dissected wings from Drosophila melanogaster fruit flies were used as the hydrophobic, laser energy strongly absorbing sample substrates. Using untreated substrates produces predominantly molecular [M + K](+) ions of the FFAs, whereas other alkali metal adducts can be generated by treating the wings with the corresponding alkali hydroxide before spotting of analyte. Limits of detection for the positive ion mode were determined for mixtures of isolated FFAs to values in the low 10 pmol range. Specific values depend on chain length and degree of unsaturation. R(2) coefficients for the analysis of saturated FFAs were found to be generally close to 0.98 over about 3 orders of magnitude if an internal standard (15:0 FFA) was added. Semiquantitative analyses of mixtures containing unsaturated FFAs are also possible but require more effort on the calibration strategy. Notably, both saturated and (poly-)unsaturated FFAs are detected sensitively in the presence of relatively high concentrations of other physiologically abundant lipids (phospholipids and triacyclglycerols). This simplifies screening of the FFA composition in crude tissue extracts. This feature is demonstrated by the analysis of a crude liver extract and that of fingermarks.
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Affiliation(s)
- Alexander Pirkl
- Institute for Hygiene, University of Münster , Robert-Koch-Straße 41, 48149 Münster, Germany
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Evaluation of a commercial enzymatic test kit regarding the quantitative analysis of different free fatty acids. Anal Bioanal Chem 2014; 406:7401-5. [DOI: 10.1007/s00216-014-8162-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 08/27/2014] [Accepted: 09/03/2014] [Indexed: 11/26/2022]
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12
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Mass spectrometry and inflammation—MS methods to study oxidation and enzyme-induced changes of phospholipids. Anal Bioanal Chem 2013; 406:1291-306. [DOI: 10.1007/s00216-013-7534-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 11/14/2013] [Accepted: 11/21/2013] [Indexed: 10/25/2022]
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13
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Napagoda M, Rulíšek L, Jančařík A, Klívar J, Šámal M, Stará IG, Starý I, Šolínová V, Kašička V, Svatoš A. Azahelicene Superbases as MAILD Matrices for Acidic Analytes. Chempluschem 2013; 78:937-942. [DOI: 10.1002/cplu.201300258] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Indexed: 11/12/2022]
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14
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Eibisch M, Riemer T, Fuchs B, Schiller J. Differently saturated fatty acids can be differentiated by 31P NMR subsequent to derivatization with 2-chloro-4,4,5,5-tetramethyldioxaphospholane: a cautionary note. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:2696-2700. [PMID: 23414224 DOI: 10.1021/jf305186x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The analysis of free fatty acid (FFA) mixtures is a very important but, even nowadays, challenging task. This particularly applies as the so far most commonly used technique-gas chromatography/mass spectrometry (GC/MS)-is tedious and time-consuming. It has been convincingly shown ( Spyros, A.; Dais, P. J. Agric. Food Chem. 2000, 48, 802 - 5) that FFA may be analyzed by (31)P NMR subsequent to derivatization with 2-chloro-4,4,5,5-tetramethyldioxaphospholane (CTDP). However, it was also indicated that differently unsaturated FFAs result in the same (31)P NMR chemical shift and cannot be differentiated. Therefore, only the overall fatty acid content of a sample can be determined by the CTDP assay. In contrast, we will show here by using high-field NMR (600 MHz spectrometer, i.e., 242.884 MHz for (31)P) that the CTDP assay may be used to differentiate FFAs that have pronounced differences in their double bond contents: saturated fatty acids (16:0), moderately unsaturated (18:1, 18:2), highly unsaturated (20:4), and extremely unsaturated fatty acids (22:6) result in slightly different chemical shifts. The same applies for oxidized fatty acids. Finally, it will also be shown that the CTDP derivatization products decompose in a time-dependent manner. Therefore, all investigations must adhere to a strict time regime.
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Affiliation(s)
- Mandy Eibisch
- Medical Faculty, Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
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