INVESTIGATION OF METAL ATTACHMENT TO POLYSTYRENES IN MATRIX-ASSISTED LASER-DESORPTION IONIZATION

Cationization is essential to the matrix-assisted laser desorption ion ization time-of-flight (MALDI-TOF) mass spectrometry analysis of a var iety of synthetic polymers. This work studied polystyrene cationizatio n in MALDI using the salts of eight different metals. It was found tha t only the salts of silver, copper, and palladium produced good metal- polystyrene cation signals. More interestingly, it was observed that M ALDI could also produce metal-rich cluster cations and that the presen ce of polystyrenes tended to suppress formation of the metal-rich clus ter cations. Based on these results and others, we propose that polyst yrene cationization may proceed through gas-phase metal attachment rea ctions under the conditions used. With this argument, we were able to better explain a reported experimental observation that showed a stron g cation concentration effect on measured molecular weight distributio ns of polystyrenes. (C) 1998 American Society for Mass Spectrometry.