Can anyone tell me what could be causing changes in mass spectral ratios. Tune parameters are the same, methods the same, sample prep the same. Happened with more than one compound of interest.
Yet have major ions ratios flipped. New base peak. See it on 4 different GCMS. The GCMS we have are 73, 75C and 77A.
For years the spectra matched published standards.
I'm trying to figure out what brought on this recent change.