Ions derived from linear polysulfide oligomers using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Abstract

Attempts to produce detectable levels of ions from oligomers of linear polysulfides (LPs) H(SC 2H 4OCH 2OC 2H 4S) n H ( n up to 24) by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry failed with all common matrix/cation combinations except 9-nitroanthracene containing silver trifluoracetate. The latter matrix yielded a series of species assigned to Ag(SC 2H 4OCH 2OC 2H 4S) n representing the loss of two thiol hydrogen atoms, together with smaller quantities of other series Ag(SC 2H 4OCH 2OC 2H 4S) n (C 2H 4OCH 2OC 2H 4S) and Ag(SC 2H 4OCH 2OC 2H 4S) n (SC 2H 4O C 2H 4O CH 2OC 2H 4S) when a conventional LP was utilised. Other LP structures were examined and these also gave argentated species; one LP (designated ZL-2264) gave a spectrum featuring silver isotope splitting of all of its peaks. At higher laser powers, or with high silver salt concentrations, or after extensive ageing of samples prior to laser irradiation, a totally new series of peaks emerged attributed to [(Ag 2S) n Ag] + with n reaching 11, i.e. containing 23 silver atoms.