Hello all,

I developed several LC-MS method using a Waters Xevo TQ mass spectrometer. I mostly use the ESI interface in positive mode.

Once an ingineer from Waters told me that for certain compounds it could be worthwile setting the capillary voltage to 0.5 kV in positive mode instead of the usual 3-3.5 kV in order to increase the response. In several instances I effectively obtained significantly better response with this low capillary voltage. Those methods worked very well and were fully validated. However the matrix was always rather simple.

I wonder what would be the outcome of a capillary voltage set to 0.5 kV for plasma samples. Could there be a detrimental effect on the method's performance due to poor ionization of matrix components?

Thank you for your thoughts,

Babar