Dissolved organic matter (DOM) is
an ultracomplex mixture of organic
compounds in the land/ocean–atmosphere interface. Normally,
polar compounds from DOM are hardly retained by liquid chromatography
(LC) columns for further analytical purposes. Here, we utilized Fourier
transform ion cyclotron resonance mass spectrometry with LC for online
analysis of DOM in river water and rainwater. With sophisticated instrumental
optimization, different portions of metal salts, carboxyl-rich alicyclic
molecules, organosulfates (OSs), and lignin-like compounds could be
fully fractionated within one LC cycle (20 min). The complexity of
the analyte was greatly reduced by LC separation, which therefore
allows much better MS performance. Moreover, the compounds’
structures were characterized by tandem mass spectrometry (MS
n
). The protocol presented herein offers a
novel insight into the conventional LC-MS method, that it has the
potential to investigate OSs and other components in DOM according
to specific functional groups and heteroatoms and to explore their
potential sources and reaction mechanisms.