Is it advisable to backflush a reverse phase C18 with a 100% MeOH? How does this effect the column life and separation?

Hello John,
in general you do such a procedure only when your column packing already shows some bad effects. Most columns show a flash on the lable, which indicates the flow direction. This flash shows also the flow direction when the column is packed. Many people say you should only use your column in this direction. But over the years column packing technology has improved, and we can say, that the packing density is the same over the bed length of the column (almost). And please, if you backflush your column, never connect this column during this procedure to your detector, to monitor what's coming out of your column! Service costs for your detector will cost you more than to purchase a new column.
Gerhard

Typically we have done this when the column has shown bad effects...tailing, baseline anomilies, etc, and pump to a waste container. Could you explain more about the potential damage to the detector that you mentioned? I had never heard of this. Thanks

Hi John,
if some particles (or unsolved compounds)have blocked your column frit and the top of the packing, than, when you backflush, these particles can block the In-capillary of your detector. In general the inner diameter of capillaries used is about 0,1mm! This can happen very often with RI detectors, but also with UV detectors.
Gerhard