ValueError: Unknown precursor m/z from USI. Specify the precursor m/z directly.

[chinmayaNK22]

ValueError: Unknown precursor m/z from USI. Specify the precursor m/z directly.

[bittremieux]

Some public repositories (notably MassIVE) only return the peak values, whereas spectrum_utils also requires having a valid precursor m/z value. Therefore, if the spectrum for your USI is only available on MassIVE and not on alternative repositories, you might encounter this error. In that case you can specify the precursor_mz directly in the from_usi call, as mentioned in the error message.

However, we had a workaround for this by retrieving USIs from MassIVE through the GNPS resolver as well to fill in missing precursor m/z values. This currently needs a small update (see #52), and will be fixed in the next upcoming release.

For now either specify the precursor m/z directly or retrieve USIs from repositories other than MassIVE.

[chinmayaNK22]

Thank you Bittremieux

That was quite informative. I will try to work with other repositories for now.

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Chinmaya