Halohydrination of epoxy resins using sodium halides as cationizing agents in MALDI‐MS and DIOS‐MS

Abstract

Halohydrination of epoxy resins using sodium halides as cationizing agents in matrix-assisted laser desorption/ionization (MALDI) and desorption ionization on porous silicon mass spectrometry (DIOS-MS) were investigated. Different mass spectra were observed when NaClO(4) and NaI were used as the cationizing agents at the highest concentration of 10.0 mM, which is much higher than that normally used in MALDI-MS. MALDI mass spectra of epoxy resins using NaI revealed iodohydrination to occur as epoxy functions of the polymers. The halohydrination also occurred using NaBr, but not NaCl, due to the differences in their nucleophilicities. On the basis of the results of experiments using deuterated CD(3)OD as the solvent, the hydrogen atom source was probably ambient water or residual solvent, rather than being derived from matrices. Halohydrination also occurred with DIOS-MS in which no organic matrix was used; in addition, reduction of epoxy functions was observed with DIOS. NaI is a useful cationizing agent for changing the chemical form of epoxy resins due to iodohydrination and, thus, for identifying the presence of epoxy functions.

Mass Spectrometry of Synthetic Polymers

“…They showed that the sensitivity and molecular weight distribution (MWD) is comparable to MALDI mass spectra obtained with the 2,5-dihydroxybenzoic acid (2,5-DHB) matrix. The same group investigated the halohydrination of epoxy resins using sodium halides as cationizing agents in MALDI and desorption ionization on porous silicon (DIOS) MS. With the use of deuterated methanol as the solvent, it was shown that the hydrogen atom source was probably ambient water or residual solvent, rather than being derived from matrixes . Another way of obtaining homogeneous sample preparations could be the miniaturization of sample spots , .…”

Soft ionization mass spectroscopy: Insights into the polymerization mechanism

“…Halohydrination of epoxy resin has been observed when some halogenated sodium salts (NaI and NaBr) have been used as cationizing agents. This halohydrination is not seen with NaCl because chlorine is less nucleophilic than bromine or iodine 62. For polymers that are not easily ionizable, it may be necessary to chemically derivatized them prior to measurement 63–65.…”