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Why Does Matrix‐assisted Laser Desorption/Ionization Time‐of‐flight Mass Spectrometry Give Incorrect Results for Broad Polymer Distributions?
Author(s) -
Martin K.,
Spickermann J.,
Räder H. J.,
Müllen K.
Publication year - 1996
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/(sici)1097-0231(199609)10:12<1471::aid-rcm693>3.0.co;2-x
Subject(s) - dispersity , polymer , chemistry , desorption , mass spectrometry , analytical chemistry (journal) , ionization , molar mass distribution , mass spectrum , molecular mass , fragmentation (computing) , matrix assisted laser desorption/ionization , time of flight mass spectrometry , polymer chemistry , chromatography , organic chemistry , ion , adsorption , operating system , computer science , enzyme
Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) is known to give reliable results for narrow molecular weight distributions, though in the case of polydisperse polymers the values obtained are not in agreement with those from conventional methods. In this paper we simulate broad polymer distributions with increasing polydispersity by mixing equimolar amounts of either poly(styrene) (PS) or poly(methylmethacrylate) (PMMA) standards in a mass range between 5000 and 100 000 Da with increasing difference in molecular weight. This allows us to investigate the problems of MALDI‐TOF measurements of polydisperse polymers. We found that several reasons are responsible for the false results. High molecular weight polymers require higher laser power for the desorption/ionization process than do low molecular weight polymers. This causes smaller peak areas for the high mass component and can also be responsible for fragmentation of the low molecular weight part of a mixture, if the molecular weights of the polymers are widely distributed. The observed dependence upon laser power is different for PS and PMMA polymers and changes with the matrix used. Furthermore, doubly charged molecular peaks and molecular cluster peaks appear in the spectra and influence the experimentally measured distribution.