Influence of the matrix on analyte fragmentation in atmospheric pressure MALDI.
In this paper, we report the measurement of the degree of analyte fragmentation in AP-MALDI as a function of the matrix and of the laser fluence. The analytes include p-OCH3-benzylpyridinium, three peptides containing the sequence EEPP (which cleave very efficiently at the E-P site), and three deoxynucleosides (dA, dG, and dC), which lose the neutral sugar to give the protonated base. We found that the matrix hardness/softness was consistent when comparing the analytes, with a consensus ranking from hardest to softest: CHCA >> DHB > SA approximately THAP > ATT > HPA. However, the exact ranking can be fluence-dependent, for example between ATT and HPA. Our goal here was to provide the scientific community with a detailed dataset that can be used to compare with theoretical predictions. We tried to correlate the consensus ranking with different matrix properties: sublimation or decomposition temperature (determined using thermogravimetry), analyte initial velocity, and matrix proton affinity. The best correlation was found with the matrix proton affinity.
Schulz
E
E
Institute of Pharmaceutical Chemistry, Johann-Wolfgang Goethe University Frankfurt, Frankfurt am Main, Germany.
Karas
M
M
Institute of Pharmaceutical Chemistry, Johann-Wolfgang Goethe University Frankfurt, Frankfurt am Main, Germany.
Rosu
F
F
Department of Chemistry, Mass Spectrometry Laboratory, University of Liège, Institut de Chimie, Bat. B6c, B-4000, Liège, Belgium.
Gabelica
V
V
Department of Chemistry, Mass Spectrometry Laboratory, University of Liège, Institut de Chimie, Bat. B6c, B-4000, Liège, Belgium. v.gabelica@ulg.ac.be.
D001274:Atmospheric Pressure; D001672:Biocompatible Materials / Q000737:chemistry*; D009705:Nucleosides / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D001672:Biocompatible Materials; D009705:Nucleosides