Baseline stable without flow cell....really flow cell dirty?

[Anthony_Ng]

I checked an old Agilent 1050 today. It was not used for more than 5 years.

The last complaint from my team is unstable baseline. Hence I took out the flow cell and got a very stable baseline. If I put the flow cell in, the variation is around 100mAu.

Is there any possible cause, except dirty flow cell or bubble inside, will lead to such problem? (e.g. Pump? Check valve? Damper?)

[Consumer Products Guy]

I'd put the flow cell in and check it with the pump OFF, see if the baseline is OK then. We still use four 1050 systems in our lab routinely.

I think if your flow cell was dirty, then the contamination would be more steady. I'd try with pump on and with pump off for 15 minutes, report back. I'm assuming that your pump ripple is below 2 bar, no pressure fluctuations. And, yes, you could have a bubble in the flow cell. The little windows and seals in the flow cell are replaceable, not sure if they're still available.

[Alfred88]

Dear Anthony_Ng:
Since you are using this system again after long idle, let's try 4 things:
1. Acid cleaning with 10% Nitric acid. (Remove all the columns). This will clean the flow cell
2. Replace UV lamp.
3. Purge the whole flow line to remove bubbles.
4. Replace frit filters (inside MP bottles).

Additional, if pump cannot maintain pressure:
5. Replace pump seals, and piston/plungers

More problem: Call tech support.

Good luck.