C18 column installed in reverse

[marie666]

Can it be saved? A Phenomenex Gemini-NX C18 column was installed opposite to correct flow direction and run 50 minutes at 1 ml/min with a gradient of ACN & 0.1% formic acid. This type of column can be installed in reverse for regeneration purposes (according to the accompanying documentation), but at lower flow rates. Think I can try the regeneration protocol and expect a return to performance? What could this have done to the packing material? Thanks!

[lmh]

It probably hasn't done it any harm at all. The only reason not to reverse a column is if the frit that holds the packing material in place on the inlet side of the column has bigger pores than the particle size of the column material (because in this case the reverse flow would pump out the material). If your column can be reversed to regenerate, the inlet frit must have smaller pores. The reduced flow rate for regeneration is probably based on the idea that you're regenerating because the back-pressure has gone up, because the column is partially blocked (hopefully at the inlet end), so it's probably best to pump a little slower than normal while the blockage clears. If you didn't go over the column's working-pressure, you won't have done it any damage.
But the best thing in any case is to run a test-sample the right way round and check column performance is as expected.