Infrared matrix-assisted laser desorption/ionization mass spectrometry with a transversely excited atmospheric pressure carbon dioxide laser at 10.6 µm wavelength with static and delayed ion extraction
✍ Scribed by Christoph Menzel; Stefan Berkenkamp; Franz Hillenkamp
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 134 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0951-4198
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✦ Synopsis
Infrared matrix-assisted laser desorption/ionization mass spectrometry (IR-MALDI-MS) at 10.6 mm wavelength with static and delayed ion extraction is reported. A compact, sealed-off transversely excited atmospheric pressure carbon dioxide laser system with an output energy of 10 mJ per pulse and an initial spike of 70-90 ns duration was used for the experiments. An Er:YAG laser (! = 2.94 mm, t = 90 ns) in the infrared and a frequency-tripled Nd:YAG laser (! = 355 nm, t = 15 ns) in the ultraviolet (UV) were employed for comparison. A direct comparison of MALDI-MS in the reflectron mode of the mass spectrometer showed less metastable fragmentation for IR-MALDI with the CO 2 laser as compared to UV-MALDI. As a result mass spectra of large biomolecules up to several hundred kilodalton (KDa) in mass with a mass resolution exceeding 100 (FWHM) were obtained in a reflectron time-of-flight mass spectrometer. A mass resolution of up to 7000 (FWHM) and a mass accuracy of a few ppm for peptides is shown with delayed ion extraction. Analytical sensitivity for CO 2 -MALDI-MS is in the low femtomole range. Mass spectra of gel-separated and electroblotted proteins desorbed directly from a PVDF membrane and of a double stranded DNA of 515 base pairs with the CO 2 laser are shown as examples for applications.