Effects of Mass Spectroscopic Parameters on Electrospray Ionization Mass Spectra of Size-Factions from a Soil Humic Acid

摘要

In recent years, atmospheric pressure ionization (APCI and ESI) has been increasingly used for the mass spectrometric (MS) investigation of naturally occurring organic matter such as humic matter. ESI-MS has been mostly applied to aquatic humic samples either in direct infusion or after separation by Size Exclusion Chromatography (SEC), while the use of APCI has been more limited. The interest in soft ionization methods is due to the assumed occurrence of unfragmented humic ions without formation of artifacts. No direct evidence was found for fragmentation of humics in the ion source, thereby undermining a possible cause of artificial low molecular mass ions.'