Impact of instrument and experiment parameters on reproducibility of ultrahigh resolution ESI FT-ICR mass spectra of natural organic matter

Natural dissolved organic matter (OM) is a complex heterogeneous mixture of compounds that have defied traditional characterization using standard analytical methods. Electrospray ionization mass spectrometry, particularly in ultrahigh resolution mode, provides a new platform for compositional assessment of this important pool of the Earth's reduced carbon. Here, we propose a framework for optimization of instrument and experiment parameters for high quality data acquisition using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). We report the impact of these parameters on reproducibility of peak detection and repeatability of peak height in replicate injections of Suwannee River fulvic acid (FA), a common terrestrial OM standard. In addition, we examine the variability in peak detection and peak height among different types of experimental replicates of dissolved OM derived from laboratory cultures of Candidatus Pelagibacter ubique, a ubiquitous marine α-proteobacterium.