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Understanding and Optimizing the MALDI Process Using a Heated Sample Stage: a 2,5-Dihydroxybenzoic Acid Study

Published

Author(s)

Mark Arnould, William E. Wallace, R Knochenmuss

Abstract

Since its use as a compound for matrix assisted laser desorption/ionization (MALDI), 2,5 dihydroxybenzoic acid (DHB) has been the subject of many solid state and gas phase studies. Here, the temperature of DHB during LD experiments was raised from +20C to +160C and ion production measured as a function of temperature, while a residual gas analyzer (RGA) monitored neutral production. Heating readily sublimes microcrystalline samples, like those from hand spotting, due to high surface area. Single crystals were employed in the LD experiments, which offer stability under vacuum at high temperatures due to lower surface to volume ratios and planar faces. The data from the LD spectra at increasing temperatures provides insight into desorption and ionization mechanisms that occur during the MALDI process.There are 4 distinct ions produced during LD of a single crystal of DHB and they are: m/z 137 ([DHB-H2O]+), m/z 154 ([DHB] +), m/z 155 ([DHB+H]+) and a condensation/dehydration product observed at m/z 273 ([2DHB-2H2O+H]+) or di-esterification. The graph of total ion production remains constant from 20?C until 60?C, where it increases almost exponentially and maximizes at 100C. Ion production at this point is 3 times that at room temperature (RT). The graph then decreases sharply to a local minimum at 120?C but is still twice that at RT. Finally, as temperature increases, ion yield increases to a second maximum at 140?C and is 4 times that observed at RT. Ion production decreases beyond 140C due to crystal decomposition from prolonged exposure to elevated temperatures
Proceedings Title
ASMS Conference on Mass Spectrometry and Allied Topics | 52nd | Proceedings of the 52nd ASMS Conference on Mass Spectrometry and Allied Topics | American Society for Mass Spectrometry (ASMS)
Volume
33(1)
Conference Dates
May 23-27, 2004
Conference Location
Nashville, TN
Conference Title
ASMS Conference on Mass Spectrometry

Keywords

crystal growth, desorption, laser desorption ionization, MALDI, mass spectrometry, organic acid, sublimation, thermal desorption

Citation

Arnould, M. , Wallace, W. and Knochenmuss, R. (2004), Understanding and Optimizing the MALDI Process Using a Heated Sample Stage: a 2,5-Dihydroxybenzoic Acid Study, ASMS Conference on Mass Spectrometry and Allied Topics | 52nd | Proceedings of the 52nd ASMS Conference on Mass Spectrometry and Allied Topics | American Society for Mass Spectrometry (ASMS), Nashville, TN, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852390 (Accessed April 19, 2024)
Created January 1, 2004, Updated February 19, 2017