Hi all
My Agilent LC-MS/MS sensitivity dropped suddenly so that calibrant ions signals are very low and reserpine signal in MRM decreased more than 10 times.
Autotune is done without any problem.

Ion source and ion guide (octapole) were cleaned several times, capillary and horn were replaced by new ones, HED and collision cell were cleaned, and new needle was used for spray. Spray is very good. There is nothing I've not done.

Strange thing that happens is that sometimes, ions with masses greater than 900 were filtered suddenly by quad 2 in scan or profile mode and I have no signal for them.
I don't know is there any relation between this behavior of quad 2 and low sensitivity of the instrument.

Any idea?