RID/Column problem - unstable baseline

[FBProc]

I'm having problems with my HPLC RID and/or columns after not using it for about 2 years.

I had two columns sitting in the compartment one a Phenomenex Rezex Monosaccharide Ca2+ (ion exchange) and the other a Zorbax XDB-C8.
Both were used for sugar analysis, the eleunt for the Rezex was 18mohm H2O and the C8 was 75% ACN, they were probably sitting in this mobile phase for 2 years. And there is a possibility the columns were sitting in the wrong type of mobile phase for that period. I spent ages flushing out with IPA and then the mobile phase. Initially the RID kept getting unbalanced even after purging the reference cell multiple times. Seems ok now but I'm still getting funny readings, I'd like to show some chromatograms but don't know if it's possible to upload photos here.

Anyway the Rezex seems to have a non-fluctuating baseline though it slowly changes but it's a straight line. However I put in sugar standards 1% of fructose, glucose and sucrose and the peaks overlap a lot which shouldn't occur on a monosaccharide column, also a 1% maltose standard produced a badly tailed peak. The XDB-C8 has a very wavy baseline, up and down which is noticeable at the 100,000 nRIU scale. I switched the XDB-C8 to a Zorbax C18 and same thing with the wavy baseline as the XDB-C8.

[Gerhard Kratz]

Does that mean that your HPLC system was also not in use for 2 years, but under 100% water??????
Calcium hydroxide is now coming from your IEX column. All the Ca2+ columns will show that.
Disconnect your RID from that column and rinse for minimum 24 hours, best with an extra pump.
First off all please take into account what are the costs for one man one day in the lab???
Buy new columns and do maintenance on your HPLC system. RID needs to be rinsed, flow cell window replaced and tubing cleaned.
Check pump head sealing's, pistons etc.!
Try to run your Rezex column then with reversed flow, but please first with a slow flow rate. Maybe you can rescue that column. But still not connected to your detector for minimum 7 column volumes.
And please don't do that again to your HPLC system and to your HPLC columns. Store columns as recommended by the manufacturer in the column care guide. Good luck.

[tom jupille]

I'd like to show some chromatograms but don't know if it's possible to upload photos here.

The instructions are in the third thread of this section titled, appropriately enough, "How to embed chromatograms and reports".

[FBProc]

Does that mean that your HPLC system was also not in use for 2 years, but under 100% water??????
Calcium hydroxide is now coming from your IEX column. All the Ca2+ columns will show that.
Disconnect your RID from that column and rinse for minimum 24 hours, best with an extra pump.
First off all please take into account what are the costs for one man one day in the lab???
Buy new columns and do maintenance on your HPLC system. RID needs to be rinsed, flow cell window replaced and tubing cleaned.
Check pump head sealing's, pistons etc.!
Try to run your Rezex column then with reversed flow, but please first with a slow flow rate. Maybe you can rescue that column. But still not connected to your detector for minimum 7 column volumes.
And please don't do that again to your HPLC system and to your HPLC columns. Store columns as recommended by the manufacturer in the column care guide. Good luck.

thanks for the advice, worked like a charm the Rezex Ca2+ is saved! Any idea on how to restore the Zorbax Carbohydrate C18 column?
would running IPA through the system be enough to clean the RI? Seems fine though, good baseline. By the way it's the manufacturer's recommendation that the RCM Monosaccharide column is stored in pure water. It is also shipped with pure water. Being one man in an educational lab don't have much time to always maintain the instruments

[Gerhard Kratz]

IPA to rinse the RI flow cell should be ok. I know that the manufacturer recommends water to store the column. But they think that the column, when delivered, is always in use. A 20% organic modifier like IPA, Methanol or ACN will help. I'm happy that you could save the column.