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Ion detection limitations to mass resolution in matrix‐assisted laser desorption time‐of‐flight mass spectrometry
Author(s) -
Brown R. S.,
Gilfrich N. L.
Publication year - 1992
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290061112
Subject(s) - chemistry , mass spectrometry , time of flight mass spectrometry , resolution (logic) , ion , ion mobility spectrometry–mass spectrometry , desorption , chromatography , time of flight , analytical chemistry (journal) , matrix (chemical analysis) , selected reaction monitoring , tandem mass spectrometry , adsorption , organic chemistry , artificial intelligence , ionization , computer science
The ion detection process in a discrete‐dynode electron multiplier can result in significant mass resolution losses in time‐of‐flight mass spectrometry (TOF‐MS) for higher mass‐to‐charge (m/z) ion species. This resolution loss is attributed to propagation time delays and signal broadening in the ion detector. This is presumed tobe due to the generation o a distribution of secondary ion species produced initially upon impact of a primary ion with the first ynoe surface of the ion detector. Comparisons are made between the signals produced by a standard discrete dynode ion detector (which amplified the negatively chqrged species produced by impact of a primry ion) and a detector modified to respond to only the positively charged secondary ion species produced by a primary ion impact. Ion signals for higher m/z ions with the standard detector geometry are see to be due to a narrow signal component, most likely due to the generation o secondary electrons and/or very low mass secondary ions (H − ), and a broad signal component, apparently due to secondary ions which take signifiant amounts of time to traverse the low potential fields between the first and second detector dynode. This results in ion signal tailing for higher m/z ion species. Numerical subtraction of the ion signal obtained with the standard and modified detector geometries (singly protonated molecular ion species of equine myoglobin) results in an improvement in mass resolution, such that a new adduct ion species (from trifluoroacetic acid) can be resolved.