I am trying to develop a method using an uncoated bare fused silica capillary. The run buffer I am currently using is a 10mM KPO4 pH 2.5 buffer. However, I am having problems that I can't seem to figure out. There has been inconsistencies between runs, sometimes the peaks show up and sometimes they don't. Also MT time seems to drift when it does work. I have first believed it was insufficient capillary coniditioning (I have been rinsing for 40psi for 5 min. between injections, and allowing for multiple prerun injections), but this has not helped. Now I'm thinking that it might just be the nature of the uncoated capillary, and maybe I could increase the concentration of the run buffer to help fix the disappearance of the peaks. Can anybody help explain why I am experienceing this phenomenon?