By anonymous on Thursday, July 22, 2004 - 02:32 pm:

We are getting a severe baseline elevation after the elution of arginine at 28 min until the end of the run. 5 runs overnight were good/normal. PH1 was replaced and this elevation was observed. We put the previous good PH1 buffer on and the elevation was still present. Hence, it appears to be in the instrument instead of the buffer. Any ideas with the battle of the L-8000 would beneficial! Are there any users of this instrument out there?

Thank you

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By Anonimous on Tuesday, July 27, 2004 - 08:13 am:

We have seen this problem before, we have tried to replace all buffers and it worked, but it happened again after a while. The regeneration of the ammonia column worked, but just for a period of time. We think it is due to ammonia that is somehow accumulating in the buffers and column and "eluting" at the end of the run. We even tried to correlate its apparition with the cleaning of the laboratory with ammonia containing products but were not successful. If you find out what the problem is, we would be glad to know in case it happens again. Thanks

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By anonymous on Wednesday, August 4, 2004 - 09:11 am:

We had successful runs switching just the B1 buffer to new buffer manufactured with a new lot of citric acid. The old citric acid must have had a small impurity undetectable by our raw material testing that accumulated in the system over the length of the run. The new B1 works wonderously.

Do you use your instrument continuously? What kind of buffers do you use? We use both the sodium PH buffers, where we had a problem, and also the lithium based PF buffers.
Cheers.

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By Steve Watts on Wednesday, August 25, 2004 - 11:18 am:

The ammonia column removes ammonia from the buffers, and over time it will need to be replaced. The rise in the baseline near Arg is often due to the ammonia column. This phenomenon is listed in the Troubleshooting section of the Main Unit manual (which I find very useful and refer to on a regular basis).

Abnormal baseline shifts, etc. can also be due to a number of other factors. First, it could be eluting a non-amino acid component from the separation column once the system switches to a particular buffer. You can try cleaning the column by back-flushing with B5/R3 at 70C for 30 minutes or so. Second, if you are making your own buffers or modifying your buffers, then one of the raw materials used could be the problem. Watch out for dirty glassware as well. If you can correlate the occurence with a recent repacement of a buffer bottle, then you may have contaminated one or more of the buffers if you did not let the system slowly depressurize completely before loosening the bottle cap. This would cause obvious peak shifts as well.

So, there are a few ideas that I have thrown at you to think about. Other scenarios can also exist. I hope these comments have helped.

Steve Watts
AAA Product Specialist
Hitachi High Technologies America
steve.watts@hitachi-hta.com