preparative column packing

[vmocko]

I'm looking for advice regarding packing of preparative (2.5cm ID x 25cm) column with Styrene-divinylbenzene resin (sulfonic acid functional group). Couple of questions:
1. resin shrinking/swelling - is there some general trend i.e. shrinks more in buffer of higher concentration or pH. Should I pack at highes shrinking to achieve tight packing?
2. When the column is slurry packed, then mobile phase flows through to achieve settling of the bed, is it beneficial to reverse the flow on the column??

Any tips or tricks on preparative column packing you can share or tips on literature would be highly appreciated.
Thanks!

[tom jupille]

1. resin shrinking/swelling - is there some general trend i.e. shrinks more in buffer of higher concentration or pH.

Other things being equal, pH has little effect. The resin will shrink at higher buffer concentration (you can visualize this as an osmotic effect sucking the water out of the resin). The resin will shrink/swell as you convert from one ionic form to another. The volume depends on the degree of hydration of the counterion, so generally the H+ form is the smallest, and the resin swells for other ionic forms. The degree of swelling depends on the crosslinking of the resin (lower crosslinking allows more shrink/swell).

Should I pack at highest shrinking to achieve tight packing?

No single answer there. Depends on the crosslink, the counterion, and the buffer concentrations to be used. If two much swelling occurs after the column has been packed, you could see flow/pressure problems.

2. When the column is slurry packed, then mobile phase flows through to achieve settling of the bed, is it beneficial to reverse the flow on the column??

My experience has been that if the column has been well packed in the first place, the flow direction does not matter.

[M. Farooq Wahab]

I'm looking for advice regarding packing of preparative (2.5cm ID x 25cm) column with Styrene-divinylbenzene resin (sulfonic acid functional group). Couple of questions:
1. resin shrinking/swelling - is there some general trend i.e. shrinks more in buffer of higher concentration or pH. Should I pack at highes shrinking to achieve tight packing?
2. When the column is slurry packed, then mobile phase flows through to achieve settling of the bed, is it beneficial to reverse the flow on the column??

Any tips or tricks on preparative column packing you can share or tips on literature would be highly appreciated.
Thanks!

Packing charged particles is rather a non-trivial.
1. Resin shrinking or swelling is dependent upon its cross-link. You don't need to worry if your cross-link is rather high (modern IC resins have ~ 55% cross-link).
2. It does not matter. If you have used relatively high pressure for packing then reversing will not have any effect.

I can suggest few things if you tell us a little bit more: What is the particle size and what is the cross-link? Is your resin porous or non-porous. In the meanwhile you can have a look at a recent work on packing high efficiency resins.

http://www.sciencedirect.com/science/ar ... 7312016688

Regards,
Farooq