HELP : negative baseline drift on RI detector

[h.piatkowski@comalc.com]

Hi Folks,

I need some help.. I run fermentation samples for analysis using a BioRad Aminex HPX-87H column with a 0.02 N H2So4 eluant. Very low pH

I recenty pickedup an Agilent 1100 HPLC with a RI detector. I have an older 1049 RI running on my other machine and we have no baseline issues with it. With this new one I constantly get a negative baseline drift, it starts at 0 and always ends in the negative.. Here is what it looks like :



Any ideas how I can fix this up?

Also, I get a small negative peak after my large sugar peaks. There are 4 sugars that have very large peaks. Any of my other compounds do not show these negative peaks.. any ideas?? I increased the temp of the detector from 35 C (my old setings on the 1049) to 55 C (closer to my clumn which is at 60 C), and these have decreased, but they are still there..



I would appreciate hearing about any ideas you might have that I could try to fix these issues..

Thanks in advance for all your help..

- Hubert

[tom jupille]

Ideally, your mobile phase, column, and detector temps should all match. Since increasing the detector temp to be closer to the column temp seems to help, I'd go all the way.