Laser desorption/ionization mass spectrometry techniques

Guinan, T., Kirkbride, R, Pigou, P.E., Rond, M., Kobus, H., Voelcker, N.H. (2015) Surface-assisted Laser Desorption Ionization Mass Spectrometry Techniques for Application in Forensics. Mass Spectrom. Rev. 34 627-640. 

The most discriminating technique for proving the identity and purity of analyte peak of a chromatogram, especially for analyzing biological samples and natural products, is by using online LC-UV/MS or GC-MS/FTIR methods [15]. Alternatively, one could use a combination of TLC and MS, where direct determination on the TLC plates is made by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) [16]. 

Other MS based analytical approaches have occasionally been applied to ancient resin samples, in particular for paint varnishes. Such techniques include FABS (fast atom bombardment mass spectrometry) [35], MALDI (matrix assisted laser desorption-ionization mass spectrometry) and GALDI (graphite assisted laser desorption-ionization mass spectrometry) [36 38]. 

Two recently developed mass spectrometric techniques have had a major impact on the analysis of large biomolecules matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS). MALDI-MS was first introduced by Karas and Hillenkamp66 and Tanaka et al.61 in 1988 and has experienced an exponential development. It has become a widespread soft ionization technique for bioorganic samples, especially large biomolecules. Fenn and co-workers68 first published the successful soft ionization technique for... 

Separation techniques in hyphenation with elucidation of the structure of organometallic compounds [electrospray ionization-mass spectrometry (ESI-MS) and matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS)]... 

Kussmann M, Nordhoff E, Rahbek-Nielsen H, Haebel S, Rossel-Larsen M, Jakobsen L, Gobom J, Mirgorodskaya E, Kroll-Kristensen A, Palm L, Roepstorff P (1997) Matrix-assisted laser desorption/ionization mass spectrometry sample preparation techniques designed for various peptides and protein analytes. J Mass Spectrom 32 593-601... 

Burrell M, Earnshaw C, Clench M (2007) Imaging matrix assisted laser desorption ionization mass spectrometry a technique to map plant metabolites within tissue at high spatial resolution. J Exp Bot 58(4) 757-763. doi 10.1093/jxb/erll39... 

Other techniques, such as capillary electrophoresis and [matric-assisted laser desorption ionization] mass spectrometry, provide qualitative analyses, often with greater speed and sensitivity. Nevertheless, AAA by high-performance liquid chromatography (HPLC) complements other structural analysis techniques, such as peptide sequencing, and remains indispensable for quantifying proteinaceous materials. 

Elucidation of degradation pathways and identification of transformation products (TPs) is of crucial importance in understanding their fate in the environment and requires the employment of advanced instrumental techniques. Analytical methods that can be used for this purpose include Uquid chromatography with diode array or fluorescence detector (LC-DAD/FL), nuclear magnetic resonance (NMR), infrared spectroscopy (IR), matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), gas... 

Kussmann, M., Nordhoff, E., Rahbek-Nielsen, H., Haebel, S., Rossel-Larsen, M., Jakobsen, L., Gobom, J., Mirgorodskaya, E., Kroll-Kristensen, A., Pahn, L., and Roepstorff, R, Matrix-assisted laser desorption/ionization mass spectrometry sample preparation techniques designed for various peptide and protein analytes, Journal of Mass Spectrometry, 32, 593-601, 1997. 

The proof of Equations (5.49) and (5.50) can be found in the references [54,56]. Note, incidentally, that other techniques for measuring the MMD, such as MALDI (matrix-assisted laser desorption ionization mass spectrometry) will have a different relation between the signal and the MMD. Note also that the assumption that the GPC signal is proportitHial to the mass of polymer depends on what sort of detection is used for example, this will not hold if the detector is sensitive just to the end-group of a polymer chain. 

We have named our approach Eragmentation Matrix-Assisted Laser Desorption/ Ionization mass spectrometry, or simply E MALDI MS, because it is the fragmentation fragments that are emphasized in the study. The technique should be applicable to any solid when the proper operating conditions are employed. 

Dissociation and ionization by means of one or several lasers. Sensitive detection of fragments and ions with resonance photoionization and mass spectrometric techniques (tunable lasers). Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) with pulsed ablating laser sources. High lateral resolution enables molecular microprobing of biological cell compounds... 

Gobom,)., Nordhoff, E., Mirgorodskaya, E., Ekman, R., and Roepstorff, P. (1999) Sample purification and preparation technique based on nano-scale reversed-phase columns for the sensitive analysis of complex peptide mixtures by matrix-assisted laser desorption/ ionization mass spectrometry. J. Mass Spectrom., 34,105-116. 

Of the two related techniques, FAB found far greater use in studies of enantioselective discrimination as compared to other desorption/ionization methods, such as MALDI and secondary ion mass spectrometry (SIMS). Chan and coworkers demonstrated enantiodiscrimina-tion of amino acids by a-, P-, and y-cyclodextrins using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) [28]. The observed levels of enantioselectivity were found to be dependent on the size of cyclodextrin cavities, as well as on the length and functionality of the amino acid side chain. Vairamani and coworkers demonstrated discrimination of amino acid methyl esters using various monosaccharide hosts by liquid secondary ion mass spectrometry (LSIMS) [29]. It is curious that more work has not been done using these sources. MALDI, in particular, is a simple and straightforward technique. Various researchers have demonstrated the observation of noncovalent complexes [30-32], for example, between peptides and proteins, but relatively little work has been performed that focuses on studying enantioselective noncovalent interactions by MALDI-MS. 

Direct Laser Desorption/Ionization Mass Spectrometry (LDI-MS) An alternative technique used to eliminate matrix and cationization salt effects is LDI. 

Mass spectrometry is the only method that delivers the mass of a molecule, as the ratio of molecular mass to the number z of charges per molecule. Until recently mass spectrometry was of little use for the analysis of polymers, since polymers could not be vaporized in the spectrometer without thermal decomposition. However, newer techniques, such as matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), which uses a volatile carrier, the matrix, to transport nonvolatile polymers to the magnetic field of the spectrometer, allow the determination of molecular masses of polymers up to 200,000. 

Law KP (2010) Laser desorption/ionization mass spectrometry on nanostructured semiconductor substrates DIOS (TM) and QuickMass (TM). Int J Mass Spectrom 290 72-84 Law KP, Larkin JR (2011) Recent advances in SALDI-MS techniques and their chemical and bioanalytical applications. Anal Bioanal Chem 399 2597-2622 Lewis WG, Shen Z, Finn MG, Siuzdak G (2003) Desorption/ionization on silicon (DIOS) mass spectrometry background and applications. Int J Mass Spectrom 226 107-116 Li Q, Alonso R, Renner SA, Winefordner JD, Powell DH (2005) Desorption/ionization on porous silicon mass spectrometry studies on pentose-borate complexes. Anal Chem 77 4503-4508 Lin Z, Zhang S, Zhao M, Yang C, Chen D, Zhang X (2008) Rapid screening of clenbuterol in urine samples by desorption electrospray ionization tandem mass spectrometry. Rapid Commun Mass Spectrom 22 1882-1888... 

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