Hi
We bought a used Dionex DX-120 several months ago and set it up to run anions with no problems. Then we switched to cations(CS 16, 38mM MSA, 1.0ml/min)and found that the baseline was getting clipped at the bottom of the chromatogram. The baseline with or without zeroing is 0 and it gives a flat electronic signal. If I inject a 25ug/ml cations standard the peaks are all present , at the correct retention time, and the peaks would appear to be about the right area except when they come down to the baseline they go flat and part of the peak is clipped off..Ive tried the auto offset switch on and off , and most of the other dipswitches thinking its an electronic issue with no success. We did learn that the DX-120 does not properly rinse between eluent changes so we now take out the eluent, replace with DI water and flush the system for ~30 minutes before putting the new eluent in and switching from column a to b.
I would appreciate any help you folks might have!
Thanks!
Eric