by
attica » Wed Feb 13, 2008 9:30 am
Hi
Could you please give some more info, when does your gradient kick in, ( 20mins into the run?) if so the check valves on the relevant gilson pump B or A need replaced. It also could be that the volume of the mixing chamber on the gilson pump is not set to a suitable volume (too low). therefore incorrect mixing. Could also be a leak leting in air.
Does your detector have a back presssure regulator on the flow output to stop air bubbles forming in the flowcell? - causing noise
If you are using unipoint and you have the lamp turning off (at end) and on ( at start) as part of the method then it could be that the lamp is taking 20 mins to reach its max light then fluctuating intensity, then the lamp is at fault.
The best way to troubleshoot a noisy baseline is as follows:
run the method injecting a blank and when the noise starts stop the pumps. if the noise continues the lamp is faulty ( change the lamp) if the baseline flattens the pump is faulty change the inlet and outlet check valves on the gradient pump. if the pressure fluctautes on any of the pumps when running alone then the check valves need changed.
hope this helps a bit.
