Molecular mass determinations in coal-derived liquids by MALDI mass spectrometry and size-exclusion chromatography

摘要: Abstract This study examined the effect of changes in instrument-related parameters on mass spectra obtained by MALDI-m.s.: ion-extraction voltage, laser power and sample loading. Results were compared with those size-exclusion chromatography (s.e.c.) using 1-methyl-2-pyrrolidinone as mobile phase. A coal tar pitch its pyridine-soluble pyridine-insoluble fractions used samples. MALDI-mass no added matrix, since absorbed strongly at wavelength, 337 nm. Higher extraction voltages (up to 30 kV) led observation higher masses whole fraction, where presence higher-molecular-mass material was indicated s.e.c. Increasing ion voltage served only accelerate species already ionized, without otherwise disturbing sample: use must be therefore considered providing a more complete inventory ionized species. level loading target similar spectra, although there indications that for both these parameters, results might longer improve (and eventually deteriorate) beyond optimum values, which appear sample-dependent. The low-power revealed structural information low masses, series homologous peaks could observed, high power.