RT Journal Article
SR Electronic
T1 Systematic analysis of in-source modifications of primary metabolites during flow-injection time-of-flight mass spectrometry
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.09.28.509873
DO 10.1101/2022.09.28.509873
A1 Niklas Farke
A1 Thorben Schramm
A1 Andreas Verhülsdonk
A1 Hannes Link
YR 2022
UL http://biorxiv.org/content/early/2022/09/28/2022.09.28.509873.abstract
AB Flow-injection mass spectrometry (FI-MS) enables metabolomics studies with a very high sample-throughput. However, FI-MS is prone to in-source modifications of analytes because samples are directly injected into the electrospray ionization source of a mass spectrometer without prior chromatographic separation. Here, we spiked authentic standards of 160 primary metabolites individually into an Escherichia coli metabolite extract and measured the thus derived 160 spike-in samples by FI-MS. Our results demonstrate that FI-MS can capture a wide range of chemically divers analytes within 30 seconds measurement time. However, the data also revealed extensive in-source modifications. Across all 160 spike-in samples, we identified significant increases of 11,013 ion peaks in positive and negative mode combined. To explain these unknown m/z features, we connected them to the m/z feature of the (de-)protonated metabolite using information about mass differences and MS2 spectra. This resulted in networks that explained on average 49 % of all significant features. The networks showed that a single metabolite undergoes compound specific and often sequential in-source modifications like adductions, chemical reactions, and fragmentations. Our results show that FI-MS generates complex MS1 spectra, which leads to an overestimation of significant features, but neutral losses and MS2 spectra explain many of these features.HighlightsFI-MS enables measurements of chemically divers metabolites.Extensive in-source modifications during electrospray ionization are detected by FI-MS.A network approach explains 49 % of all recorded in-source modifications.Competing Interest StatementThe authors have declared no competing interest.