Hello, I am currently developing a new lcmsms method for the quantification of 20 drugs and their metabolites. I have optimised the compounds of interest and am having trouble with Sertraline and Norsertraline.

Both have very similar product ions and when I used 292 as a precursor ion for Norsertraline, 6 product ions were produced but with very low abundances.

From looking at some literature, others have used 275 as a precursor ion for as it produces much higher abundances for product ions, however I am concerned as this is also a product ion for Sertraline.

Please can someone advise as to why 275 performs better.

Thank you