Maintenance #1: Column care and storage condition

I chanced upon some notes I got from a seminar from a long time ago, some column care procedure for sharing.

1. On backpressure
Always pump mobile phase from low flow, say 0.1ml/min then increase to normal flow rate.
Back pressure must typically be kept at <3500 psi (conventional HPLC columns and systems)
UPLC columns have higher pressure limits (more than or equal to 9000 psi)
In the event of high backpressure, reverse flush column.

2. On equilibrating column
Equilibrate column with mobile phase for 10-30 column volumes.
(Ion-pair containing mobile phase may require long to equilibrate.)

3. On sample preparation
Filter samples, 0.2um or 0.45 syringe filters, guard column
Sample cleanup, SPE, protein precipitation and so on.

3. On column storage
Never store columns with buffers, in long term.

Flush with 10 column volumes of mobile phase without buffer to remove buffer and salts.
Flush with 10 column volumes of mutually miscible solvent such as Methanol and ACN.
Flush with 20 column volumes of strong solvent, THF or IPA to remove strongly adsorbed sample components.
Reverse the process and equilibrate with mobile phase.
(Who has the time to do that?!)

Typical solvent storage conditions for silica-based columns:
Reverse phase: ACN/Water (65:35)
Normal phase: IPA or hexane
Ion-exchange: Methanol
SEC or Diol: 0.05% NaN3 in Water or 10% Methanol

With good column care maintenance, you can
- extend column lifetimes
- ensure optimal column performance
- minimizes downtime!

Till next time.