Dionex HPLC problems can somebody help?

[djaydearz]

I walked into the lab this morning to be greated by a large puddle in the room. I had ran a very long sequence the night before and was popping in to top up the MP.

I looked at the chromatography of what had run and it was poor.

The check valves were leaking, so i cleaned them up and re-tightened.

Now the pressure keeps jumpping from 1300ish psi to 2000+psi and back and forth. I have primed it for ages and there are no air pockets so it seems. I am a bit clueless as to why the pressure keeps jumping high and back down. Could it be that ive doen the check valves too tight? i had to do them quite tight else they leaked. Or is it somthing to do with the column? (ie buggered).

Im sorry I am fairly new to all of this so there might be an obvious answer, would really appreciate some advise from people with more experiance

Cheers James

[bisnettrj2]

Being that your issue seems to stem from your leaking check valves, I would say it has to be a priming issue. You might want to try priming with something viscous, like isopropanol, to try to force any residual air out of your system. If you have a restriction capillary, I would put that in place of the column so you have some back-pressure on the pump while you're trying to force the air out.

[tom jupille]

It is possible to deform check valves by overtightening (ask me how I learned that! ). Check valves should be tightened to the manufacturer's specified value using a torque wrench. I would try bisnettrj2's suggestion first. If that doesn't work, try loosening and re-torquing the check valves. If *that* doesn't work, replace them.