Investigation into dissolved neutral sugars and their microbial conversion in natural and artificially produced dissolved organic matter using ion chromatography with pulsed amperometric detection and reversed-phase liquid chromatography-high resolution mass spectrometry

Ion-exchange chromatography with pulsed amperometric detection (IEC-PAD) was employed to investigate dissolved neutral sugars and their microbial conversion in both artificially prepared dissolved organic matter (ADOM), and naturally occurring dissolved organic matter (DOM) obtained from seawater and freshwater sources. The analysis of ADOM and naturally occurring DOM samples using IEC-PAD resulted in chromatograms suggesting very similar composition, each characterised by three early eluting peaks, the latter of which being a broad co-elution of multiple compounds. For naturally occurring DOM, several sugars, including arabinose, glucose, galactose, xylose and ribose, could also be identified. The three distinctive peaks obtained from IEC-PAD of ADOM were collected and further analysed by means of reversed-phase high performance liquid chromatography-high resolution mass spectrometry (RPLC-HRMS), the latter showing that glucose was totally consumed during microbial production of ADOM and potentially transformed into higher molecular weight materials and CO₂.