We have changed our uplc column today and some of you may be interested in how many injections we have made on this column. It was last changed in April and since then it has had an incredible 17,105 injections on it!
Not only that but our samples are mostly microbial fermentation broths and our standard sample preparation is to add an equal volume of acetonitrile and centrifuge. We do not filter these samples.

The details - it is a Waters Acquity UPLC BEH Shield RP18, 2.1x50mm. Our standard run is a 3 minute gradient from 5% acetonitrile to 95% with both the acetonitrile and water containing 0.1%formic acid (When we run in base we switch to column2). The column is protected by an inline filter and guard column either or both of which get changed as and when needed. Our standard injection volume is 1ul.

I would be interested to hear if other people get similar numbers of injections before their columns are changed.