I have Agilent 1100 with ESA Coulochem electrochemical detection and I analyse metanephrine in urine.
I recorded the normal pressure in system (without column) cca 30-50 bar depending on used solvent.
However, the pressure increased up to 200 bar couple days ago. I think that I found the reason.
Probably electrochemical cells are clogged.
I tried to sequentially flush with water, methanol, acetonitrile and back to methanol all at a rate of 1 mL/minute for 10 minutes each.
The pressure dropped back to cca 30 bar.
Unfortunately, when I used a fresh water or mobile phase after cleaning the cells, the presure increased more than 100 bar and it is unstable.
Water and mobile phase were fresh.
Could anybody explain it, please?