Direct sample fraction deposition using electrospray in narrow-bore size-exclusion chromatography/matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for polymer characterization

A direct sample fraction deposition method was developed for off-line size- exclusion chromatography (SEC)/matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. By using electrospray, the SEC el uent, together with a suitable matrix solution added coaxially, was directl y deposited on the MALDI plate, Owing to the formation of very small drople ts in electrospray, solvent evaporation is much faster. The fractionation v olume in narrow-bore SEC, which can directly be collected in one MALDI spot , can easily be optimized in the range of a few microlitres, In addition, f airly homogeneous sample spots were obtained. The possible influence of com position variation of the SEC effluent on the analytical results using dire ct fraction deposition was investigated; no substantial effects were observ ed. The applicability of the method was demonstrated by characterizing a br oad poly(methyl methacrylate) sample. Copyright (C) 2000 John Wiley & Sons, Ltd.