Chromatography Forum

I'm going to use a new column (Zorbax Eclipse XDB-C18). What should I do to the column? I'm confused about column activation.
Here is another situation, I was using same kind of column. But didn't do any activation. I used 10% Methanol for 30 minutes and after that ran standard solution of drug using Acetonitrile and PBS (0.1 M, 7 pH) 30:70 mobile phase.
This how I prepared the PBS,
NaH2PO4 (5.52 gm) 200 ml------Took 195 ml
Na2HPO4 (16.63 gm) 310 ml------ Took 305 ml

Total 500 ml + 500 (Distilled water) = 1000 ml PBS

After few minutes the pressure was too much high.
Later, I checked my column with another machine just to check using 10% Methanol the pressure was also high.
I need your guidance that how to activate my new column and how can I recover the used one.

There is no need to "activate" a new column. It is shipped in methanol/water usually, so any methanol/water miscible mobile phase can be used. You can use a % organic that is similar as the storage condition for the beginning, but this is not a must.
My guess is that your phosphate salts are dirty and you did not filter the mobile phase before use. There may be dust clogging the inlet frit of the column.
Try to back flush the column with filtered high aqueous eluent (say H2O/ACN 15/85) and see if pressure gets down again. If you don't have the equipment to filter mobile phases, don't use phosphate buffer or at least get yourself an inline filter of a precolumn.
Jörg

If the column was shipped in 100% organic solvent and you pump a fairly concentrated salty buffer straight in, it's possible the solvent in the column precipitated the buffer as soon as it entered, which would give a high back-pressure. If you have a column in 100% organic, you might want to flush a little water through it before using a lot of salt.