Validation and Evaluation of High-Resolution Orbitrap Mass Spectrometry on Molecular Characterization of Dissolved Organic Matter

Abstract

Molecular composition of dissolved organic matter (DOM) is a hot topic in subjects such as environmental science and geochemistry. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been applied to molecular composition characterization of DOM successfully. However, high instrument and maintenance costs have constrained its wider application. A high-resolution Orbitrap mass spectrometer (Orbitrap MS) can provide approximately 500,000 resolving power (at m/z 200), which is potentially capable of characterizing the molecular composition of DOM. In this paper, the application of highresolution Orbitrap MS was evaluated by comparing with FT-ICR MS in the aspect of resolution, mass distribution, detection dynamic range, and isotopic peak intensity ratio. The impact of instrument parameters of Orbitrap MS was further investigated, which includes ionization, ion transfer, and mass detection. The result shows that the high-resolution Orbitrap MS is capable or even preferable for molecular characterization of DOM. However, the peak intensity distributions are dependent on the instrument parameters, which could affect the environmental impact assessment caused by the sample itself. The result indicates that development of a universal and comparable method is of great demand.

An international laboratory comparison of dissolved organic matter composition by high resolution mass spectrometry: Are we getting the same answer?

“…The weight-averaged metric values of commonly detected ions can be used to assess instrument tuning bias, particularly with regards to average mass and oxygenation. Saturation levels (H/C or AI mod ) were more consistent across instruments and can be used as effective guides for instrument comparability, or may be used as benchmarks to gauge tuning acceptability for new instruments to give results in a context comparable to those of the international community (Pan et al 2020).…”

“…It is clear that a great effort would be required to obtain virtually identical mass spectra for complex DOM mixtures among laboratories. Instruments can be initially tuned to modify the "analytical window" that is covered (Kew et al 2018a;Pan et al 2020), but it is conceptually difficult to decide a priori what the desired spectrum should look like. Here we begin this effort by establishing the averages and ranges obtained at the status quo, including the presence of commonly detected ions and weight-averaged metric values of these ions.…”

“…Since Fievre et al collected the first HRMS spectrum of DOM in 1997 (Fievre et al 1997), there have been large increases in both the number of researchers using HRMS for DOM analysis and the variety of instrument types being employed. This upward trend has been facilitated by the propagation of commercial Fourier transform ion cyclotron resonance (FT-ICR), Orbitrap, and high-resolution quadrupole time of flight (q-TOF) mass spectrometers (Hawkes et al 2016;Lu et al 2018;Pan et al 2020). While the application of HRMS for the molecular-level assessment of DOM continues to grow, leading to improved methods that are adopted by the research community, so do the challenges with data comparison and interpretation that arise from the use of instruments with different resolving powers (mass/[full width at half maximum] at m/z centroid; m/Δm), source conditions, ion optics, and users.…”

Laboratory In-Situ Production of Autochthonous and Allochthonous Fluorescent Organic Matter by Freshwater Bacteria

“…Dissolved organic matter (DOM) is an essential component of global biogeochemical cycles. DOM is a highly complex chemical composite [ 1 ], and quantitative chemical analyses of DOM composition requires the use of high resolution quantitative techniques, such as Fourier-Transform Ion-Cyclotron-Resonance Mass Spectrometry (FTICR-MS) coupled with High-Performance Liquid Chromatography (HPLC) [ 2 , 3 , 4 , 5 ]. Optical techniques for the interrogation of DOM characteristics and dynamics are increasingly used by researchers due to the ease of data collection through time and space [ 1 , 6 ].…”

Structural Characterization of Dissolved Organic Matter at the Chemical Formula Level Using TIMS-FT-ICR MS/MS

“…Analytical approaches integrating ultrahigh-resolution mass spectrometry, gas/liquid preseparation techniques, and tandem mass spectrometry strategies have provided much of the existing information on the chemical diversity of DOM. ,− An online HPLC-Orbitrap MS/MS method developed by Hawkes et al was used in an attempt to isolate single compounds in DOM samples from different ecosystems. Although the ubiquitous nature of DOM isomeric complexity was demonstrated, the proposed procedure was unable to separate individual compounds and differentiate fragmentation patterns from specific isomers of the same chemical formula.…”