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Qualitative and quantitative end‐group analysis of a small molecular weight polyester by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Author(s) -
Laine Olli,
Österholm Heidi,
Järvinen Hannele,
Wickström Kim,
Vainiotalo Pirjo
Publication year - 2000
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(20000331)14:6<482::aid-rcm900>3.0.co;2-a
Subject(s) - chemistry , alkali metal , polyester , mass spectrometry , carboxylate , desorption , matrix assisted laser desorption/ionization , end group , matrix (chemical analysis) , polymer chemistry , salt (chemistry) , inorganic chemistry , analytical chemistry (journal) , polymer , organic chemistry , chromatography , copolymer , adsorption
Matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry was used for qualitative and quantitative end‐group analysis of a small molecular weight polyester, poly(2‐butyl‐2‐ethyl‐1,3‐propylene phthalate). The presence of carboxyl‐terminated linear and cyclic polyester oligomers was confirmed with the help of simple sample preparation methods. The presence of carboxyl end‐groups in the polyester chains was verified through their formation of carboxylate salts with alkali metal cations. Cyclic oligomers were identified through deuterium exchange of the exchangeable protons of the polyester. Various inorganic salts were tested for salt formation of the carboxyl end‐groups, but only the alkali metal salts proved effective. The influence of the alkali metal salts on the results of the quantitative end‐group analysis was also studied. The relative amounts of differently terminated and cyclic oligomers were calculated when the alkali metal salts were used with different matrices. The results showed that both the salts and the matrices used in sample preparation can have a marked effect on the quantitative results of the end‐group analysis. The measurements were carried out using 2,5‐dihydroxybenzoic acid (DHB), 1,8,9‐trihydroxyanthracene (dithranol), and 2‐(4‐hydroxyphenylazo)benzoic acid (HABA) as matrix compounds. Dithranol and HABA repeatably exhibited similar results, and these results differed from those obtained with DHB probably because of the different ionization mechanisms in the MALDI process. Copyright© 2000 John Wiley & Sons, Ltd.