Natural organic matter (NOM) is a highly complex mixture of organic molecules that is an important component of marine, freshwater and glacial ecosystems. H, C, O, N, S in NOM exist in various classes containing isotopes. Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) is an excellent technique for molecular level analysis of NOM. Furthermore, ESI-FTICR combined with liquid chromatography (LC) is a promising approach to obtain chemical information about NOM molecules.

In this study, preconditioning, flow rate, and column were selected as variables to optimize the NOM analysis method. When a sufficient amount can be injected, LC-MS analysis using multiple injection is effective for low concentration analysis. In this study, NOM was detected when the injected amount was 1.0 μg. PTFE filter was used for preconditioning, and the most compound was detected when using UPLC HSS T3 100mm and flow rate 0.3 mL/min. Multiple injection approach is comparatively more than 10 times faster to Solid Phase Extration (SPE), indicating greater time efficiency. The data provided in this study can be used as a guideline for researchers analyzing the trace level of NOM.