Matrix‐assisted laser desorption/ionization of high‐mass molecules by Fourier‐transform mass spectrometry

Abstract

Following the first demonstrations of high‐mass analysis using time‐of‐flight matriz‐assisted laser desorption/ionization (MALDI) techniques by Hillenkamp,^1,2 Tanaka³ and their co‐workers, there have been significant efforts in a number of laboratories to adapt the new methodology to Fourier‐transform mass Spectrometry (FTMS). The motivation fsor this research is obvious. Namely, it would be desirable to couple the unparalleled high mass resolution of FTMS⁴ with the extended mass range proveded by MALDI, paricularly for analysis of polymers and biomolecules. Unfortuanately, Prior to the presnt work, attempts to mate FTMS and MALDI have met with limited success. The highest mass matrix‐assisted laser‐desorption‐FTMS result previously obtained appears to be the unpublished low resolution spectrum of bovine insulin recently reported by russell co‐workers.⁵ We,⁶ Campana and co‐workes,⁷ and Hettich and Buchanan^8,9 have had some sucess with MALDI‐FTMS of biomolecules with masses lower than 3000 Da.⁹ Fruthermore, with single exception of Campana's report of obtaining mass resolutiojn of 5000 for the moleculer ion of melittin,⁷ such spectra have not displayed high resolution. Here, we report successful development of MALDI‐FTMS, demonstrated with spectra obtained from a variety of high‐mass polymer and biomolecule samples, using 355nm radiation from an excimer‐pumped dye laser for desorption/ionization and sinapinic acid as matrix, Some of these spectra are of much higher mass resolution than is possible with current time‐of flight mass spectrometers.