Matrix assisted laser desorption/ionization reflectron

Kaufmann R, Chaurand P, Kirsch D, Spengler B. Post-source decay and delayed extraction in matrix-assisted laser desorption/ionization-reflectron time-of-flight mass spectrometry. Are there trade-offs . Rapid Commun Mass Spectrom 1996 10 1199-1208. 

Kaufmann, R., Chaurand, R, Kirsch, D., and Spengler, B., Post-source Decay and Delayed Extraction in Matrix-assisted Laser Desorption/Ionization-Reflectron Time-of-Flight Mass Spectrometry. Are There Trade-offs , Rapid Comm. Mass. Spectrom., 10, 1199, 1996. 

Matrix assisted laser desorption ionization time-of-flight (MALDI-TOE) mass spectrometry was carried out with a PerSeptive Biosystems Voyager-DE-RP MALDl-TOF mass spectrometer. A 337-nm UV nitrogen laser producing 3-ns pulses was used in the reflectron mode. The samples were prepared by mixing 10 pi of a 0.1 M HAc solution of the sample with 20 pi of a solution of 3 mg/1 a-cyano-4-hydroxy cinnamic acid in wafer. One pi of that solution was loaded on the gold-sample plate. 

Kaufmann, R., Spengler, B., and Lutzenkirchen, R, Mass spectrometric sequencing of linear peptides by product-ion analysis in a reflectron time-of-flight mass spectrometer using matrix-assisted laser desorption ionization. Rapid Communication Mass Spectrometry, 7, 902-910, 1993. 

From the very beginning, time-of-flight mass spectrometers have had a reputation as low-resolution instruments. The plasma desorption and matrix-assisted laser desorption-ionization instruments that are currently popular today produce mass spectra with resolutions from 300 to 800 that often appear to be dependent upon the nature or quantity of the sample or (in the case of MALDI) the laser power. Extraordinary mass resolutions of up to 1 part in 25,000 have been demonstrated using reflectrons, but have been by no means routine. The problem is that the time-of-flight axis reflects many properties of an ion in addition to its mass, including uncertainties in the time of ion formation, its initial location in the extraction field, its initial kinetic energy (before acceleration), and metastable fragmentation. 

Strobel, F.H. Solouki, T. White, M.A. Russell, D.H. Detection of Femtomole and Sub-Femtonaole Levels of Peptides by Tandem Magnetic Sector/Reflectron Time-of-Flight Mass Spectrometry and Matrix-Assisted Laser Desorption Ionization. J. Am. Soc. Mass Spectrom. 1991,2,91-94. 

Demelbauer, U.M., Zehl, M., Plematl, A., Allmaier, G. and Rizzi, A., Determination of gly-copeptide structures by multistage mass spectrometry with low-energy collision-induced dissociation comparison of electrospray ionization quadrupole ion trap and matrix-assisted laser desorption/ionization quadrupole ion trap reflectron time-of-flight approaches. Rapid Commun. Mass Spectrom., 18, 1575-1582 (2004). 

Lee, H. Lubman, D. M. Sequence-specific fragmentation generated by matrix-assisted laser desorption/ionization in a quadrupole ion trap/ reflectron time-of-flight device. Anal. Chem. 1995,... 

With the advent of very sensitive ionization techniques such as matrix assisted laser desorption (MALDI) coupled with time-of-flight (TOF) mass analysis, measurement of the intact mass of peptides at sub-pmol levels has become a reality (2) of which we have taken advantage for the systematic screening of HPLC fractions. Partial sequence information can be obtained by carrying out enzymatic hydrolysis with exoproteinases (e.g. carboxypeptidases and aminopeptidases) (3, 4). More recently, MALDI has been used to measure metastable decomposition occurring in the first field free region of a reflectron TOF instrument (referred to as post source decay (PSD)) with only marginally more sample (5-7). 

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