Hi Peter, Most of the time it is just a clogged top filter. While the column is running, loosen the top o-ring by loosening the black knob on the top. Once that is done, carefully unscrew the white threaded adapter several turns to back the top filter off the resin bed. You can then unscrew the red top cap and remove the top assembly. Replace the nylon filter, the part number should be with the column literature. If you think it is required you can stir up the top 1mm of the resin bed and remove it. Then add some water to the top, reassemble, run the column a little to settle the resin, then lower the adapter and tighten all connections.
Here is the link to the packing reservoir for the XK columns which gives more detailed instructions in case you need to do a full repack: https://www.gelifesciences.com/gehcls_images/GELS/Related%20Content/Files/1 340181598294/litdoc28992023_20120626104814.pdf Good Luck, Chris -- Christopher L. Colbert, Ph.D. Assistant Professor Department of Chemistry and Biochemistry North Dakota State University P.O. Box 6050 Dept. 2710 Fargo, ND 58108-6050 PH: (701) 231-7946 FAX: (701) 231-8324 On 7/12/12 8:51 PM, "Peter Hsu" <hsuu...@u.washington.edu> wrote: >Hi all, > >Sorry for the slew of offtopic posts, but does anyone here have any >experience repacking the large 120mL Superdex75/200 columns? Any >advice/tips on doing it? I've got an older column that's gotten clogged >while washing w/NaOH (can't go over 0.1mL/min w/o getting overpressure >alarm), and not sure the bossman would be thrilled w/buying another >column. > >Thanks for any ideas. > >Peter >
