Usually I had pressure on 40 bar (+/- 2). But, recently I forced with a problem of pressure increasing after 20 minutes the pressure increasing up to 55 and then decrease. We analyze mixture of oil and phosphatides .it occurs in both cases injection of a sample and blank. Have you ever forced with such a problem? What could be the reason ?
Pump : Quat Pump VL (G7111A)
Detector: 1260 infinity || ELSD (G4260B)
Column: 250 X 4.6 mml S-5 μm.
We use gradient with 3 phases:
B: Methanol, Acetic acid, Triethylamine
C: Acetone,Acetic acid, Triethylamine