Abstract
Desorption ionization on porous silicon-mass spectrometry (DIOS-MS) was applied to the analysis of various polymer additives, including ultraviolet absorbers (UVA), hindered amine light stabilizers (HALS), hindered phenol type primary antioxidants, and thioether type and phosphite type secondary antioxidants. First, molecular weight distribution and detailed chemical structure of an oligomer type UVA with poly(ethylene glycol) (PEG) main chain could be characterized based on the clearly observed DIOS mass spectrum without interference peaks. Then, to enhance ionization efficiency of the additive samples, the use of cationization salts such as sodium iodide (NaI) and silver trifluoroacetate (AgTFA) was investigated. In spite of the use of cationization salts, nitrogen-containing additives such as UVA and HALS tended to form [M+H]+ peaks. However, for the other additives, the use of cationization salts served to enhance the formation of molecular-related ions: hindered phenol type and thioether type antioxidants preferred the formation of [M+Na]+ in the presence of NaI, whereas phosphite type antioxidants could be observed as [M+Ag]+ ions in the presence of AgTFA.
