HPLC vs LCMS

[munkietoes]

I was wondering what would be the cause for my calibration tables made from DAD signals not correlating well with those made from the MS signal. I have two compounds I am trying to quantify, let's call them A and B. Compound A is always higher using the MS calibration curve and B lower. Any insight would be very much appreciated. Thank you in advance.

[Ary]

If I understand correctly(I wasnt 100% clear about your post) when you measure response for your compounds by MS you get a different answer than if you measure them by UV. Welcome to the house of fun. For years people have been running multiple detection systems to get a "better" answer to their quantitation problems. As of yet no-one has found an answer though many have tried and continue to try. The latest on the market is CAD though again this has its problems.

[Schmitty]

May be enhancement/suppression on the MS, it depends on the matrix. Also, if you standards are in that matrix or not for comparison.