A recent discussion with my fellow colleagues has generated this question. If one were to remove the column from the pump fitting before the pressure reading on the pump read zero, would the bed in the column be disturbed to the point that it would affect the life of the column and/or your chromatography?

If the column is well-packed, it shouldn't. But this doesn't sound like the type of question that comes up out of the blue. Was there a specific situation that prompted it?

-- Tom Jupille / LC Resources Inc.

Tom,
The background behind the question is as follows: I was taking one column off of a LC system and replacing it with another. I turned the pump flow off and before the pump pressure reading was zero, I remove the column from its fitting. My colleagues interjected when I did this because they claimed that taking a column off before the pressure reading is zero can affect the column bed. They also claim that this damage can happen no matter how well-packed the column is. I did not agree with their statement. I understand that a bed may settle a bit when a column is new, but I couldn't visualize the opposite happening. Anymore thoughts?

Tim

Nah, I'll stand by my original comment (I agree with you). The vast majority of columns can be reverse-flushed (in fact, that's the standard recommendation for dealing with a plugged inlet frit).

Anybody out there had an actual experience with damaging a column by disconnecting it too quickly?

-- Tom Jupille / LC Resources Inc.

There has been countless times that my columns have been de-pressurized very quickly (both intentionally and unintentionally) and I've never observed any degradation in chromatography. The one caveat to this is that I almost always am running gradients and the effects of any "pre-column" voids are minimized due to sample focusing early in the run.

Peace