Agilent Technologies ZORBAX Guide D'utilisation page 8

Column Care
The inlet frit on columns with a particle size of 2.7 µm or greater has a
nominal porosity of 2 µm. Samples that contain particulate matter will plug
the column inlet frit. ZORBAX and Fast Guard columns and hardware kits
(as required) are recommended for use with such samples, and are gener-
ally recommended for all column use.
See agilent.com/chem/fastguards for more information about
guard columns.
Cleaning Your Column/extending Column life
For columns that can be backflushed (Poroshell 120, ZORBAX columns
with particles >1.8 µm and all Pursuit and Polaris columns), start with a
stronger (less polar) solvent.
1. Disconnect column from detector and run wash solvents into a beaker.
2. Start with your mobile phase without buffer salts (water/organic).
Run at 10 to 20 column volumes through.
3. Next, use 100% organic (methanol or acetonitrile).
4. Check pressure to see if it has returned to normal; if not, then,
5. Discard column or consider stronger conditions,
e.g., 75% acetontrile/25% isopropanol
6. Increase to 100% isopropanol, 100% methylene chloride or 100%
hexane (if you use methylene chloride or hexane, you will need to flush
the column with isopropanol prior to use and before returning to your
reversed-phase mobile phase).
For columns with particles < 1.8 µm, do not backflush the column - replace
the column.