Chromatography Forum

hi:

I find that my bed support frit(outlet of the column side) was clogged,what is your recommedations to clean my frit?the packing is C18,5u,300A,silica based,

thanks

If your column is clogged you can back flush it with organic. This will work for awhile, but eventually you are just going to need a new column.

If the frit cannot be cleaned in the usual manner, it may be possible (albeit somewhat risky and not recommended) to replace the frit. However, it seems unusual that the outlet side is affected.



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Given that it was a 300A column, I assume you are doing larger molecule analysis, so maybe the best solution is to look at your sample preparation to ensure nothing is precipitating on the column and also blocking the column outlet frit.

For cleaning, I'd follow the recommendations of your column supplier. Some columns can't be backflushed ( inlet frit is different porosity to outlet, or perhaps because of the packing method ).

If there are no recommendations, I'd take the outlet frit off, clean it using ultrasonication, warm cleaning solutions ( appropriate for your samples ), and backflushing it, before reinstalling.

You may have to pressurise the column, and fill any void that appears at the front of the column - you can use the back section of an old guard column of the same column type.

Bruce Hamilton

Besides good suggestions above, it is often a good practice to use guard cartridges to protect your analytical column.

thanks guys!it is really useful

1. how do you know that the OUTLET frit was clogged?
2. most proposals above will help you with an INLET frit problem, but not with an outlet frit problem. For an outlet frit problem, I see only one option: replace it!

thanks Uwe Neue,that's really a good question!in fact ,I am packing a DAC column,the packing pressure is quite high as high as 1600psi!
but I guess my outlet frit was clogged because
(1)find that the packing rod just moved only a short distance then stopped there,when I unpacked the column bed I found the half of the column bed (silica)near the outlet of the column is loosen ,half of the column bed near the inlet of the column was consolidated!
(2)I repaced the outlet frit ,the packing was good!
do not know whether make myself clear?
any advice on how to clean the frit will be highly appreciated!thanks

Sorry, I didn't realise you were packing new columns.

The obvious solution is to purchase frits that have been cleaned and are rated for HPLC use. However, if the frits were OK before, maybe you should examine the one that is blocked to determine whether the blockage is particulate or gunge.

If you haven't specified the cleaanliness, you may have to try different solvents to see if any any residual process materials are present.

My suggestion would be ultrasonication in warm chloroform/methanol, followed by the same treatment with acetone.

Bruce Hamilton

OK this makes sense. Either your packing material contains an excessive amount of fines that clog the frit, or the frit is of the wrong size for the particles that you are packing, or your packing procedure is breaking particles.