The role of the laser pulse duration in infrared matrix-assisted laser desorption/ionization mass spectrometry.
The role of the laser pulse duration in matrix-assisted laser desorption/ionization mass spectrometry with infrared lasers (IR-MALDI-MS) emitting in the 3 microm wavelength range has been evaluated. Mass spectrometric performance and characteristics of the IR-MALDI process were examined by comparing a wavelength-tuneable mid-infrared optical parametric oscillator (OPO) laser of 6 ns pulse duration, tuned to wavelengths of 2.79 and 2.94 microm, with an Er:YAG laser (lambda = 2.94 microm) with two pulse durations of 100 and 185 ns, and an Er:YSGG laser (lambda = 2.79 microm) with a pulse duration of 75 ns. Threshold fluences for the desorption of cytochrome C ions were determined as a function of the laser pulse duration for various common IR-MALDI matrices. For the majority of these matrices a reduction in threshold fluence by a factor of 1.2-1.9 was found by going from the 75-100 ns long pulses of the Erbium lasers to the short 6 ns OPO pulse. Within the experimental accuracy threshold fluences were equal for the 100 and the 185 ns pulse duration of the Er:YAG laser. Some pronounced pulse duration effects related to the ion formation from a glycerol matrix were also observed. The effect of the laser pulse length on the duration of ion emission was furthermore investigated.
Menzel
Christoph
C
Institute of Medical Physics and Biophysics, University of Muenster, Germany.
Dreisewerd
Klaus
K
Berkenkamp
Stefan
S
Hillenkamp
Franz
F
D000803:Angiotensin I / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry; D006096:Gramicidin / Q000737:chemistry; D006801:Humans; D007834:Lasers; D055095:Optics and Photonics; D012710:Serum Albumin, Bovine / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
D003574:Cytochrome c Group; D004277:DNA, Single-Stranded; D006096:Gramicidin; D012710:Serum Albumin, Bovine; D000803:Angiotensin I