Column collapse is an unlikely and theorized phenomenon where a separation column can lose a significant portion of it’s separation capabilities due to multiple factors.

One way column collapse can occur is by contaminants such as proteins being retained in the column.  These contaminants would bind to the stationary phase and prevent the target compounds from being retained on the column.  Depending on the severity, target compounds’ retention times can shift slightly, or move into the front solvent peak.

Occasionally, air bubbles can form at the outlet of a column due to pressure differences at the inlet and outlet of the column, but is quite unlikely to occur.

The best course of action to take when suspecting column collapse is to wash the separation column with water and methanol.  We recommend washing with ultrapure water for 30 minutes, 100% methanol for an hour, and water again for 30 minutes, running analytical flow rate for the water washings and 80% of analytical flow rate for the methanol wash.  It might take multiple and/or longer washes to restore column activity, but in some cases the column will just need to be replaced.