Hello,

I want to create an LC-MS method for the analysis of Sudan I. I started by first manually optimizing the MS parameters. I'm using a SCIEX QTrap 6500.

When I preform a precursor ion scan (positive mode) by direct infusion I do not get the expected main precursor ion. I expect 249.1 m/z as main m/z, since the mass of sudan I is 248.1. I have add the spectrum in the attachtment.

The mass calibration should be OK, so I am looking for another explanation. Does someone have an explanation why I find 247 m/z as main precursor ion in positive mode for sudan I?

Thank you!