opening mzml file for small molecules

support
opening mzml file for small molecules robyn eisert  2025-06-10 10:53
 

Hi,

I downloaded an mzml file and the accompanying .wiff file for a small molecule. I am not very familiar with these since I do proteomics on Thermo instruments, but someone asked if I can take a look. I generated a transition file, but when I import the mzml file or the wiff file I get the errors shown below (I just removed the original name of the file for confidentiality). I am wondering if I made a mistake in the transition list or if there's a setting I got wrong since I am not as familiar with sciex or SWATH data. Is there a good tutorial that can help me out?

At 1:23 PM:
Failed importing results file 'file.mzML'.
[SpectrumList_mzML::create()] Bad istream.

At 1:48 PM:
Failed importing results file 'file.wiff'.
[SpectrumImpl::getDataSize()] Could not open data stream. Is a required 'scan' file missing?

Thanks!

 
 
Nick Shulman responded:  2025-06-10 15:02
A .wiff file usually cannot be read on by itself. It normally requires there to be another file whose name ends in ".wiff.scan".

For mzML files, we have seen the "Bad istream" error when the file has been edited by hand, because the numbers in the <index> towards the end of the file are pointing at invalid locations in the file.
You can find more information about that error here:
https://github.com/ProteoWizard/pwiz/issues/1592
-- Nick