So far I am trying the LC-MSMS MRM to quantify my sample, before the training engineer comes, I can do the LOQ is 300 pg, the training engineer changed the spray needle, ion transfer tube and the ion source parameters to help me increase sensitivity, but as results the result get worse, and finally I can not repeat my results with 300 pg. and the peak shape is really rough, for this circumstance what I can do to improve the sensitivity and peak shape?
Thanks!