Chromatography Forum

I performed a columns cleanup (AS-11-HC guard and separator) followed the instruction in the manual, to solve a problem of reduced retention time and floride tailing. The cleaning solution I used is 200mM in 80% Actonitrile. It didn't help. Any advices?

I also found that it took so long (>1day) to bring the background to be less than 1uS after the cleanup. Is this normal?

Thanks,
-Aster

Here are chromatograms showing my problems with retention time.
https://www.dropbox.com/s/seimgjp0j7pn4 ... e.xls?dl=0

Thanks!

Your column is probably old. Lowering the Eluent concentration and flow rate may improve peak separation.

Thanks for comments! Our columns are quite new, used for only about 400 analysis ( but some of the samples have high salinity). A lower eluent con helps a little while reduced flow rate doesn't.