bubble on top of column

[tom jupille]

Generally, silica-based packings are fairly robust with respect to pressure (unlike resin-based packings). A void space and high pressure may have related causes, but high pressure by itself won't usually collapse the bed. Your 4000SW column, with its big pores can be an exception to that generalization.

It's easy enough to check. Dig out a couple of mm worth of packing from the column inlet, replace the end fitting, and test the column to see if the pressure drops back down. The column is dead already, so there's little risk of making things worse.

[s]

hmmm...interesting idea...worth a try. i will try it sunday or monday.

so you are saying if i take out what i think is void that may be causing pressure problem and then run flow thru it and if P comes down then know that it was the void and replace void by adding more resin? Can you clarify? How will having empty space on top of column and running flow through effect column? Will resin expand into empty space?

Sue

[s]

Hi,

I went in and scooped out some resin and am replacing with new silica resin.

Question: some of what i scooped out had a very jello-like consistency. Is this normal? What could have caused it?

S

[HW Mueller]

Still would like to know how you got at this 4000SW material. Gel or wax shouldn´t be there.

[YX]

The top layer of gel might've been destroyed by chemicals under high pH. Fine particles could be generated on top of the column. When you reverse flush the column, the fine particles could block your new frit and cause high pressure. Have you tried normal flow direction after you had the high pressure problem?

[s]

I got to the resin by unscrewing the inlet fitting.

[s]

YX:
Interesting theory about pH destruciton of silica. I will check my PBS eluent pH for kicks. It should be close to 7. Do I need to worry about pH issues with methanol? I did try and run flow in the downflow direction and had encouraging flow at first (for a half hour) but then subsequently the pressure went really high and you know the story. Yesterday, I unscrewed the outleft fitting just to see if it also had jello-like consistency (like the stuff near inlet fitting) but instead, I found dry wax-like buildup. It was deep too. The column is totally shot. I am just trying to unravel the mystery. So, you think that the silica got destroyed?

I have been using FITC-labelled dextrans and nonlabelled dextrans on the column. No honey! Does pH of the sample matter? At 20ul, it shouldn't right if PBS is eluting it thru? I did have an old guard column, which people point out may be the culprit.

I would really be intersted in hearing your answers/comments on these issues. I am really confused and frustrated.

S

[s]

YX or other: is it possible that resin looks like wax b/c no flow was getting thru, causing resin to dry up? I would luv to hear all possibilities.

[HW Mueller]

Maybe some basic books on a some topics?