In
this study, Fourier transform ion cyclotron resonance mass spectrometry
(FT-ICR MS), combined with quadrupolar detection (QPD), was applied
for online liquid chromatography (LC) MS analysis of natural organic
matter (NOM). Although FT-ICR MS has emerged as an important analytical
technique to study NOM, there are few previous reports on online LC
FT-ICR MS analysis of NOM due to the long acquisition time (2–8
s) required to obtain high-resolution mass spectra. The QPD technique
provides a critical advantage over the conventional dipolar detection
(DPD) technique for LC-MS analysis because a spectrum with the same
resolving power can be obtained in approximately half the acquisition
time. QPD FT-ICR MS provides resolving powers (
) of ∼300000 and 170000 at m/z 400 with acquisition times per scan
of 1.2 and 0.8 s, respectively. The reduced acquisition time per scan
allows increased number of acquisitions in a given LC analysis time,
resulting in improved signal to noise (S/N) ratio and dynamic range in comparison to conventional
methods. For example, 40% and 100% increases in the number of detected
peaks were obtained with LC QPD FT-ICR MS, in comparison to conventional
LC DPD FT-ICR MS and direct-injection FT-ICR MS. It is also possible
to perform more quantitative comparison and molecular level investigation
of NOMs with 2 μg of a NOM sample. The data presented herein
demonstrate a proof of principle that QPD combined with LC FT-ICR
MS is a sensitive analytical technique that can provide comprehensive
information about NOM.