Chromatography Forum

We have many Agilent 1100 HPLCs in our compnay and we are now recently seeing drastic baseline drops with our validated methods in random injections. Sometimes the base line recovers and sometimes it doesnt. We are seeing this problem using both isocratic and gradient methods.

One of the current changes we did was to switch from Chemstation to Empower 2 to run our HPLCs. I know that Empower and Agilent dont really communicate well, for example there is no function in Empower to see if your degasser is on of off.

I was suspecting outgassing of the mobile phase to cause the baseline drops but if that was true then all of the injections with the drop in baseline should of corrected itself over time, we do not see this in some injections. In some injections the baseline just stays there and doesnt change back to where it should be.

I also suspected that the communication between Agilent and Empower software is not doing its job right, but if that was true then the injections that we saw baseline drops shouldnt of drifted back to the correct baseline.

When we switch over to Alliance systems the system runs perfect.

Any suggestions on how to solve this problem?

if you suspect the software then the best check is to reconnect one instrument to chemstation and see if the problemm re-occurs

Other helpful details to be provided: Is your Empower/1100 connection via serial cable, ethernet or eSAT/IN?

Are your 1100s single or dual pump units?

Define "drastic" (maybe provide a picture - an overlay of 1100 run w/ drop vs. same method on a Waters instrument?)

The systems are connected using ethernet cables which is connected to a LACE box. We gain access to the instrument using a high availibility Citrix server remotely using our desktop computers in the office.

We did a diagnostic using Chemstation connected directly to the instrument and found nothing. Agilent and a Waters tech came by and found nothing also.

I will try and find a chromatogramwith a drop in baseline.

oh yeah forgot the systems have quad pumps

We have our 1100's interfaced with TotalChrom, so we are using them in a similar way to you. I've seen some random problems before caused by analyst interaction with the hand-held controller. In our case, the problem occurred because an analyst stopped the sequence at the exact time the peak was going through the detector, which produced an odd-looking chromatogram where the peak seemed to flatten then the downslope went down beyond the original baseline and remained until the next injection.

Are you seeing the drops on multiple 1100's, or just one? I've seen some odd problems with interface boxes as well.

have used another LACE?

in general the behavior looks more like a chromatographic matter rather then a software one based on what you describe