Molecular networking with network analysis




Cross, Breeanna


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Network analysis is the analysis of a collection of elements and their relationships based on graph theory. Graph theory has become essential for identifying and understanding the relationships between compounds in mass spectrometry (MS). A molecular network is the visual display of the chemical space in MS experiments. The advancements in coupling different chromatography techniques with high resolution and mass accuracy mass spectrometer have increased the ability to produce better quality tandem mass spectrometry (MS/MS) of individual compounds in a single run. With these advancements, compounds within complex mixtures were be analyzed and detected more thoroughly using both the targeted and untargeted approaches. Further, the structures of these compounds might be able to be identified with higher confidence. Using the generated MS/MS spectra, molecular networks were developed based on the similarities of molecular structures. However, the traditional 2-dimensional network analysis is static and could not show how these compounds change with depth, time, or distance. In this study, I have created a three-dimensional (3-D) molecular network analysis software to examine how dissolved organic matter (DOM) transforms with depth, with time, or with distance to have fully understood, for example, the accumulation and reactivity of DOM in the marine ecosystem. As a proof-of-concept example, I have used 3D molecular network analysis to understand abiotic sulfurization mechanisms in marine sediments better. The abiotic sulfurization enhances organic matter preservation and proto kerogen formation at low temperatures within marine sediments. The molecular networking method presented here supports the evidence of abiotic nucleophilic addition reactions involving bisulfide (HS−) and polysulfide (HSx−) in Santa Barbara Basin sediment porewater. This 3D-molecular Network analysis technique has a great potential to reveal different transformation and degradation pathways of dissolved organic matter by various biotic and abiotic environmental perturbations.



3D Networks, Abiotic Sulfurization, Molecular Networks, Network Analysis, R



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