Structural elucidation of hydroxy fatty acids by photodissociation mass spectrometry with photolabile derivatives
Venkateswara R. Narreddula
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorPawel Sadowski
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorNathan R.B. Boase
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorDavid L. Marshall
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorBerwyck L.J. Poad
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorAdam J. Trevitt
School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522 Australia
Search for more papers by this authorTodd W. Mitchell
School of Medicine, University of Wollongong, Wollongong, NSW, 2522 Australia
Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522 Australia
Search for more papers by this authorCorresponding Author
Stephen J. Blanksby
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Correspondence
S. J. Blanksby, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia.
Email: [email protected]
Search for more papers by this authorVenkateswara R. Narreddula
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorPawel Sadowski
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorNathan R.B. Boase
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorDavid L. Marshall
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorBerwyck L.J. Poad
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Search for more papers by this authorAdam J. Trevitt
School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522 Australia
Search for more papers by this authorTodd W. Mitchell
School of Medicine, University of Wollongong, Wollongong, NSW, 2522 Australia
Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522 Australia
Search for more papers by this authorCorresponding Author
Stephen J. Blanksby
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, 4000 Australia
Correspondence
S. J. Blanksby, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia.
Email: [email protected]
Search for more papers by this authorAbstract
Rationale
Eicosanoids are short-lived bio-responsive lipids produced locally from oxidation of polyunsaturated fatty acids (FAs) via a cascade of enzymatic or free radical reactions. Alterations in the composition and concentration of eicosanoids are indicative of inflammation responses and there is strong interest in developing analytical methods for the sensitive and selective detection of these lipids in biological mixtures. Most eicosanoids are hydroxy FAs (HFAs), which present a particular analytical challenge due to the presence of regioisomers arising from differing locations of hydroxylation and unsaturation within their structures.
Methods
In this study, the recently developed derivatization reagent 1-(3-(aminomethyl)-4-iodophenyl)pyridin-1-ium (4-I-AMPP+) was applied to a representative set of HFAs including bioactive eicosanoids. Photodissociation (PD) mass spectra obtained at 266 nm of 4-I-AMPP+-modified HFAs exhibit abundant product ions arising from photolysis of the aryl–iodide bond within the derivative with subsequent migration of the radical to the hydroxyl group promoting fragmentation of the FA chain and facilitating structural assignment.
Results
Representative polyunsaturated HFAs (from the hydroxyeicosatetraenoic acid and hydroxyeicosapentaenoic acid families) were derivatized with 4-I-AMPP+ and subjected to a reversed-phase liquid chromatography workflow that afforded chromatographic resolution of isomers in conjunction with structurally diagnostic PD mass spectra.
Conclusions
PD of these complex HFAs was found to be sensitive to the locations of hydroxyl groups and carbon–carbon double bonds, which are structural properties strongly associated with the biosynthetic origins of these lipid mediators.
Supporting Information
| Filename | Description |
|---|---|
| rcm8741-sup-0001-Supporting_Information.docxWord 2007 document , 2.1 MB |
Table S1: Method 1 Gradient Fig. S1: Normalized product ion abundance from the PD266 mass spectra of HFA standards derivatized with 4-I-AMPP+. Each bar represents the normalized product ion abundance from triplicate PD mass spectra of hydroxy FAs derivatized with 4-I-AMPP+. All data were recorded under identical conditions to ensure comparable conditions (e.g., laser power and alignment). Each spectrum represents average of 50 scans acquired by direct infusion of 10 μL of the sample. Fig. S2: PD266 mass spectra of 18-carbon FA standards derivatized with 4-I-AMPP+ measured at 266 nm. The PD mass spectra represent the average of 25 scans acquired by direct infusion of of 0.5 μM sample in MeOH. PD266 mass spectra of (A) FA 18:0-4-I-AMPP+, (B) FA 18:1(9Z)-4-I-AMPP+, (C) FA 18:0(12OH)-4-I-AMPP+, and (D) FA 18:1(9Z,12OH)-4-I-AMPP+. The ions labelled in green correspond to direct photodissociation of the aryl-iodide bond, [M - I]•+. Ions shown in red are the results of prompt dissociation at sites other than the aryl-iodide motif and thus still carry iodine. The ions labelled in blue results from the secondary dissociation of the [M - I]•+ ions and are diagnostic of the location of double bonds and/or sites of hydroxylation. Note that the region between m/z 445 and 466 (corresponding to the loss of iodine) has not been magnified in these spectra. Fig. S3: CID mass spectra of isomers of C18 FA standards derivatized with 4-I-AMPP+. CID mass spectra represents average of 25 scans acquired by direct infusion of a 0.5 μM sample in MeOH. CID mass spectra are of (A) FA 18:0-4-I-AMPP+, (B) FA 18:1(9Z)-4-I-AMPP+, (C) FA 18:0(12OH)-4-I-AMPP+, and (D) FA 18:1(9Z,12OH)-4-I-AMPP+. The product ions labelled green represents HI loss; product ions labelled with red carry iodine; and blue ions involve loss of iodine with subsequent fragmentation. Fig. S4: CID (A) and PD266 (B) mass spectra of FA 18:1(9Z,12OH)-4-I-AMPP+ after deuterium exchange. Both spectra represent an average of 25 scans acquired by direct infusion of a 0.5 μM sample in MeOH-d4. Deuterium exchange was carried out by dissolving the derivative in 250 μL MeOH-d4 followed by adding 10 μL of 12 mM Cs2CO3 in MeOH-d4. The mixture was vortexed for 2 min. The product ions labelled green represents HI loss and product ions labelled with red arose before iodine loss and blue arose after iodine loss, both represents hydroxyl branching location. Fig. S5: CID mass spectra of isomers of three HETE standards derivatized with 4-I-AMPP+. The CID mass spectra represents average of 50 scans acquired by direct infusion of 0.5 μM sample in methanol. CID mass spectra of (A) 5-HETE-4-I-AMPP+, (B) 12-HETE-4-I-AMPP+, and (C) 15-HETE-4-I-AMPP+.The product ions labelled red carry iodine while those in blue represent loss of iodine as HI. Fig. S6: CID mass spectra of HEPE standards derivatized with 4-I-AMPP+. The CID mass spectra represents average of 50 scans acquired by direct infusion of 0.5 μM sample in methanol. CID mass spectra of (A) 5-HEPE-4-I-AMPP+ and (B) 15-HEPE-4-I-AMPP+. The product ions labelled red carry iodine while those in blue represent loss of iodine as HI. Fig. S7: Extracted ion chromatogram of A) m/z 613 and B) m/z 621, and corresponding PD spectra C) 15-HETE-4-I-AMPP+ and D) 15-HETE-d8-4-I-AMPP+. The product ions labelled blue carry iodine while those in red represent loss of iodine as I• (127 Da). Fig. S8: PD266 mass spectra of A) [FA 18:0(12OH)-4-I-AMPP]+, B) [FA 18:0(12OH)+Na]+, C) [FA 18:0(12OH)-H]–, D) [FA 18:1(9Z,12OH)-4-I-AMPP]+, E) [FA 18:1(9Z,12OH)+Na]+, and F) [FA 18:1(9Z,12OH)-H]– Table S1: List of eicosanoid standards used to model complex mixture analysis (all acquired from Cayman Chemicals, USA). Items highlighted red in the list are deuterated internal stanadards. 10 μL aliquots of 1 ppm FA (3.12 × 10-11 mol) of all the standards were derivatized with 4-I-AMPP+ reagent following the protocol described in the manuscript. Scheme S1: Proposed mechanism for the A) formation of m/z 184 product ion in the CID of 4-I-AMPP+ and B) formation of m/z 183 product ion in the CID of AMPP+ derivatives. |
Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
REFERENCES
- 1Zhang C, Wang K, Yang L, et al. Lipid metabolism in inflammation-related diseases. Analyst. 2018; 143(19): 4526-4536. https://doi.org/10.1039/c8an01046c
- 2Shimizu T. Lipid mediators in health and disease: Enzymes and receptors as therapeutic targets for the regulation of immunity and inflammation. Annu Rev Pharmacol Toxicol. 2009; 49: 123-150. https://doi.org/10.1146/annurev.pharmtox.011008.145616
- 3Fahy E, Subramaniam S, Brown HA, et al. A comprehensive classification system for lipids. J Lipid Res. 2005; 46(5): 839-862. https://doi.org/10.1194/jlr.e400004-jlr200
- 4Gurr MI, Harwood JL, Frayn KN. Lipids: Definition, Isolation, Separation and Detection. 5th ed. Oxford: Blackwell Science; 2002.
- 5Rouzer CA, Marnett LJ. Endocannabinoid oxygenation by cyclooxygenases, lipoxygenases, and cytochromes P450: Cross-talk between the eicosanoid and endocannabinoid signaling pathways. Chem Rev. 2011; 111(10): 5899-5921. https://doi.org/10.1021/cr2002799
- 6Smith WL, DeWitt DL, Garavito RM. Cyclooxygenases: Structural, cellular, and molecular biology. Annu Rev Biochem. 2000; 69(1): 145-182. https://doi.org/10.1146/annurev.biochem.69.1.145
- 7Spite M, Clària J, Serhan CN. Resolvins, specialized proresolving lipid mediators, and their potential roles in metabolic diseases. Cell Metab. 2014; 19(1): 21-36. https://doi.org/10.1016/j.cmet.2013.10.006
- 8Mashima R, Okuyama T. The role of lipoxygenases in pathophysiology; new insights and future perspectives. Redox Biol. 2015; 6: 297-310. https://doi.org/10.1016/j.redox.2015.08.006
- 9Kuhn H, Thiele BJ. The diversity of the lipoxygenase family: Many sequence data but little information on biological significance. FEBS Lett. 1999; 449(1): 7-11. https://doi.org/10.1016/S0014-5793(99)00396-8
- 10Sacerdoti D, Gatta A, McGiff JC. Role of cytochrome P450-dependent arachidonic acid metabolites in liver physiology and pathophysiology. Prostaglandins Other Lipid Mediat. 2003; 72(1–2): 51-71. https://doi.org/10.1016/S1098-8823(03)00077-7
- 11Anthonymuthu TS, Kenny EM, Bayır H. Therapies targeting lipid peroxidation in traumatic brain injury. Brain Res. 1640; 2016: 57-76. https://doi.org/10.1016/j.brainres.2016.02.006
- 12 LIPID MAPS® Lipidomics Gateway. https://www.lipidmaps.org/data/structure/LMSDSearch.php? Mode=ProcessClassSearch&LMID=LMFA03.
- 13Calder PC. Fatty acids and inflammation: The cutting edge between food and pharma. Eur J Pharmacol. 2011; 668: S50-S58. https://doi.org/10.1016/j.ejphar.2011.05.085
- 14Rodriguez-Antona C, Ingelman-Sundberg M. Cytochrome P450 pharmacogenetics and cancer. Oncogene. 2006; 25(11): 1679-1691. https://doi.org/10.1038/sj.onc.1209377
- 15Shono F, Yokota K, Horie K, et al. A heterologous enzyme immunoassay of prostaglandin E2 using a stable enzyme-labeled hapten mimic. Anal Biochem. 1988; 168(2): 284-291. https://doi.org/10.1016/0003-2697(88)90320-X
- 16Reinke M. Monitoring thromboxane in body fluids: A specific ELISA for 11-dehydrothromboxane B2 using a monoclonal antibody. Am J Physiol Endocrinol Metab. 1992; 262(5): E658-E662. https://doi.org/10.1152/ajpendo.1992.262.5.E658
- 17Hofer G, Bieglmayer C, Kopp B, Janisch H. Measurement of eicosanoids in menstrual fluid by the combined use of high pressure chromatography and radioimmunoassay. Prostaglandins. 1993; 45(5): 413-426. https://doi.org/10.1016/0090-6980(93)90118-Q
- 18Westcott J, Chang S, Balazy M, et al. Analysis of 6-keto PGF1a, 5-HETE, and LTC4 in rat lung: Comparison of GC/MS, RIA, and EIA. Prostaglandins. 1986; 32(6): 857-873. https://doi.org/10.1016/0090-6980(86)90095-X
- 19Murphy RC, Barkley RM, Zemski Berry K, et al. Electrospray ionization and tandem mass spectrometry of eicosanoids. Anal Biochem. 2005; 346(1): 1-42. https://doi.org/10.1016/j.ab.2005.04.042
- 20Aliwarga T, Raccor BS, Lemaitre RN, et al. Enzymatic and free radical formation of cis-and trans-epoxyeicosatrienoic acids in vitro and in vivo. Free Radical Biol Med. 2017; 112: 131-140. https://doi.org/10.1016/j.freeradbiomed.2017.07.015
- 21Mesaros C, Blair IA. Targeted chiral analysis of bioactive arachidonic acid metabolites using liquid chromatography-mass spectrometry. Metabolites. 2012; 2(2): 337-365. https://doi.org/10.3390/metabo2020337
- 22Bollinger JG, Thompson W, Lai Y, et al. Improved sensitivity mass spectrometric detection of eicosanoids by charge reversal derivatization. Anal Chem. 2010; 82(16): 6790-6796. https://doi.org/10.1021/ac100720p
- 23Berberich D, Yost R. Negative chemical ionization in quadrupole ion trap mass spectrometry: Effects of applied voltages and reaction times. J Am Soc Mass Spectrom. 1994; 5(8): 757-764. https://doi.org/10.1016/1044-0305(94)80008-1
- 24Stafford GC. Instrumental aspects of positive and negative ion chemical ionization mass spectrometry. Environ Health Perspect. 1980; 36: 85-88. https://doi.org/10.1289/ehp.803685
- 25Johnson DW. Dimethylaminoethyl esters for trace, rapid analysis of fatty acids by electrospray tandem mass spectrometry. Rapid Commun Mass Spectrom. 1999; 13(23): 2388-2393. https://doi.org/10.1002/(sici)1097-0231(19991215)13:23<2388::aid-rcm803>3.0.co;2-x
10.1002/(SICI)1097-0231(19991215)13:23<2388::AID-RCM803>3.0.CO;2-X CASPubMedWeb of Science®Google Scholar
- 26Johnson DW. Alkyldimethylaminoethyl ester iodides for improved analysis of fatty acids by electrospray ionization tandem mass spectrometry. Rapid Commun Mass Spectrom. 2000; 14(21): 2019-2024. https://doi.org/10.1002/1097-0231(20001115)14:21<2019::AID-RCM121>3.0.CO;2-2
- 27Kretschmer A, Giera M, Wijtmans M, et al. Derivatization of carboxylic acids with 4-APEBA for detection by positive-ion LC-ESI–MS (/MS) applied for the analysis of prostanoids and NSAID in urine. J Chromatogr B. 2011; 879(17–18): 1393-1401. https://doi.org/10.1016/j.jchromb.2010.11.028
- 28Bollinger JG, Rohan G, Sadilek M, Gelb MH. LC/ESI-MS/MS detection of FAs by charge reversal derivatization with more than four orders of magnitude improvement in sensitivity. J Lipid Res. 2013; 54(12): 3523-3530. https://doi.org/10.1194/jlr.D040782
- 29Sun D, Meng X, Ren T, Fawcett JP, Wang H, Gu J. Establishment of a charge reversal derivatization strategy to improve the ionization efficiency of limaprost and investigation of the fragmentation patterns of limaprost derivatives via exclusive neutral loss and survival yield method. J Am Soc Mass Spectrom. 2018; 29(7): 1365-1375. https://doi.org/10.1007/s13361-018-1924-z
- 30Sun D, Su C, Liu Y, et al. A unique collision-induced dissociation reaction of cholamine derivatives of certain prostaglandins. J Am Soc Mass Spectrom. 2018; 29(12): 2360-2367. https://doi.org/10.1007/s13361-018-2051-6
- 31Liu X, Moon SH, Mancuso DJ, et al. Oxidized fatty acid analysis by charge-switch derivatization, selected reaction monitoring, and accurate mass quantitation. Anal Biochem. 2013; 442(1): 40-50. https://doi.org/10.1016/j.ab.2013.06.014
- 32Devakumar A, O'Dell DK, Walker JM, Reilly JP. Structural analysis of leukotriene C4 isomers using collisional activation and 157 nm photodissociation. J Am Soc Mass Spectrom. 2008; 19(1): 14-26. https://doi.org/10.1016/j.jasms.2007.10.003
- 33Brodbelt JS. Photodissociation mass spectrometry: New tools for characterization of biological molecules. Chem Soc Rev. 2014; 43(8): 2757-2783. https://doi.org/10.1039/c3cs60444f
- 34O'Brien JP, Needham BD, Henderson JC, Nowicki EM, Trent MS, Brodbelt JS. 193 nm ultraviolet photodissociation mass spectrometry for the structural elucidation of lipid a compounds in complex mixtures. Anal Chem. 2014; 86(4): 2138-2145. https://doi.org/10.1021/ac403796n
- 35Pham HT, Ly T, Trevitt AJ, Mitchell TW, Blanksby SJ. Differentiation of complex lipid isomers by radical-directed dissociation mass spectrometry. Anal Chem. 2012; 84(17): 7525-7532. https://doi.org/10.1021/ac301652a
- 36Pham HT, Trevitt AJ, Mitchell TW, Blanksby SJ. Rapid differentiation of isomeric lipids by photodissociation mass spectrometry of fatty acid derivatives. Rapid Commun Mass Spectrom. 2013; 27(7): 805-815. https://doi.org/10.1002/rcm.6503
- 37Pham HT, Julian RR. Characterization of glycosphingolipid epimers by radical-directed dissociation mass spectrometry. Analyst. 2016; 141(4): 1273-1278. https://doi.org/10.1039/c5an02383a
- 38Hancock SE, Ailuri R, Marshall DL, et al. Mass spectrometry-directed structure elucidation and total synthesis of ultra-long chain (O-acyl)-ω-hydroxy fatty acids. J Lipid Res. 2018; 59(8): 1510-1518. https://doi.org/10.1194/jlr.M086702
- 39Blevins MS, Klein DR, Brodbelt JS. Localization of cyclopropane modifications in bacterial lipids via 213 nm ultraviolet photodissociation mass spectrometry. Anal Chem. 2019; 91(10): 6820-6828. https://doi.org/10.1021/acs.analchem.9b01038
- 40Madsen JA, Cullen TW, Trent MS, Brodbelt JS. IR and UV photodissociation as analytical tools for characterizing lipid a structures. Anal Chem. 2011; 83(13): 5107-5113. https://doi.org/10.1021/ac103271w
- 41Klein DR, Holden DD, Brodbelt JS. Shotgun analysis of rough-type lipopolysaccharides using ultraviolet photodissociation mass spectrometry. Anal Chem. 2015; 88(1): 1044-1051. https://doi.org/10.1021/acs.analchem.5b04218
- 42Williams PE, Klein DR, Greer SM, Brodbelt JS. Pinpointing double bond and sn-positions in glycerophospholipids via hybrid 193 nm ultraviolet photodissociation (UVPD) mass spectrometry. J Am Chem Soc. 2017; 139(44): 15681-15690. https://doi.org/10.1021/jacs.7b06416
- 43Ryan E, Nguyen CQN, Shiea C, Reid GE. Detailed structural characterization of sphingolipids via 193 nm ultraviolet photodissociation and ultra high resolution tandem mass spectrometry. J Am Soc Mass Spectrom. 2017; 28(7): 1406-1419. https://doi.org/10.1007/s13361-017-1668-1
- 44Esch P, Heiles S. Charging and charge switching of unsaturated lipids and apolar compounds using Paternò-Büchi reactions. J Am Soc Mass Spectrom. 2018; 29(10): 1971-1980. https://doi.org/10.1021/jasms.8b05694
- 45Adhikari S, Xia Y. Thiyl radical-based charge tagging enables sterol quantitation via mass spectrometry. Anal Chem. 2017; 89(23): 12631-12635. https://doi.org/10.1021/acs.analchem.7b04080
- 46Adhikari S, Zhang W, Xie X, Chen Q, Xia Y. Shotgun analysis of diacylglycerols enabled by thiol–ene click chemistry. Anal Chem. 2018; 90(8): 5239-5246. https://doi.org/10.1021/acs.analchem.8b00012
- 47Pham HT, Julian RR. Mass shifting and radical delivery with crown ether attachment for separation and analysis of phosphatidylethanolamine lipids. Anal Chem. 2014; 86(6): 3020-3027. https://doi.org/10.1021/ac403754j
- 48Narreddula VR, Boase NR, Ailuri R, et al. Introduction of a fixed-charge, photolabile derivative for enhanced structural elucidation of fatty acids. Anal Chem. 2019; 91(15): 9901-9909. https://doi.org/10.1021/acs.analchem.9b01566
- 49Liebisch G, Vizcaíno JA, Köfeler H, et al. Shorthand notation for lipid structures derived from mass spectrometry. J Lipid Res. 2013; 54(6): 1523-1530. https://doi.org/10.1194/jlr.M033506
- 50Ly T, Julian RR. Residue-specific radical-directed dissociation of whole proteins in the gas phase. J Am Chem Soc. 2008; 130(1): 351-358. https://doi.org/10.1021/ja076535a
- 51Ly T, Kirk BB, Hettiarachchi PI, et al. Reactions of simple and peptidic alpha-carboxylate radical anions with dioxygen in the gas phase. Phys Chem Chem Phys. 2011; 13(36): 16314-16323. https://doi.org/10.1039/C1CP20784A
- 52Hevko JM, Murphy RC. Electrospray ionization and tandem mass spectrometry of cysteinyl eicosanoids: Leukotriene C4 and FOG7. J Am Soc Mass Spectrom. 2001; 12(7): 763-771. https://doi.org/10.1016/S1044-0305(01)00256-2
- 53Hsu F-F. Characterization of hydroxyphthioceranoic and phthioceranoic acids by charge-switch derivatization and CID tandem mass spectrometry. J Am Soc Mass Spectrom. 2016; 27(4): 622-632. https://doi.org/10.1007/s13361-015-1328-2
- 54Harvey DJ. A new charge-associated mechanism to account for the production of fragment ions in the high-energy CID spectra of fatty acids. J Am Soc Mass Spectrom. 2005; 16(2): 280-290. https://doi.org/10.1016/j.jasms.2004.11.008
- 55Hsu F-F, Turk J. Distinction among isomeric unsaturated fatty acids as lithiated adducts by electrospray ionization mass spectrometry using low energy collisionally activated dissociation on a triple stage quadrupole instrument. J Am Soc Mass Spectrom. 1999; 10(7): 600-612. https://doi.org/10.1016/S1044-0305(99)00041-0
- 56Cheng P, Zhong D, Zewail AH. Kinetic-energy, femtosecond resolved reaction dynamics. Modes of dissociation (in iodobenzene) from time-velocity correlations. Chem Phys Lett. 1995; 237(5–6): 399-405. https://doi.org/10.1016/0009-2614(95)00364-A
