Working on mass spectrometry data analysis via xcms we stumbled on to something that we think is rather significant for our work. We think this might also help others but before we can tell if that is the case we need to test it with data from other instrument manufacturers than we currently have data from (Bruker and Sciex)

Our data is collected in profile mode with a qtof type of LC-MS instrument and we are wanting to combine multiple spectra from a run for one of our analyses. We noticed that the profile spectra is not collected with regular intervals of m/z but rather regular intervals of the flight time of the ions.

The theoretical relationship between the two (see e.g. here https://en.wikipedia.org/wiki/Time-of-flight_mass_spectrometry ) is basically flight_time = constant * m/z^2 so it is trivial to convert the m/z value to something that resembles the flight_time by applying the square root to the m/z value.

We assume this is due to the timing circuitry of the instrument as it is easier to collect data at regular time intervals.

We are very interested in finding out if this is the case for all qtof type of instruments and we are actively seeking publicly available data as well as researchers that have qtof instruments that would be willing to donate a profile spectrum run taken with their instrument. It doesn't have to be anything important, even a system suitability test or a blank, although it would be better to have some chromatographic peaks in there.

Looking through the Metabolights (https://www.ebi.ac.uk/metabolights/) data repository we have only found one experiment that collected profile mode data on a qtof instrument.

Any suggestions on other data repositories to search or volunteering a data files would be most welcome.