Dear all,
I'm trying to pack a column (200um ID, 10cm) with weak cation exchange material (5um particle size). I've tried different solvents (methanol, water, isopropanol) to prepare the slurry. That material is properly dissolved in water. I generally prepare the slurry with 12-15mg/mL of solvent. I'm packing the column by using a gas pressure (40 bar) or pushing with a pump of an HPLC (3500 psi), packing for different times (from 6h to a few days) but any of this conditions is giving me good results as resolution and separation of peaks are terrible.
Any advice?
Many thanks in advance!
Dear Bill and Michael,
thanks for your prompt response, we have used 5um particle size for other materials, such as WAX, SAX, or C18 with 200 um and I didn't have any problem, anyway, I have also 3um particle size so probably I could try also. What about the slurry? do you think the proportion of material suspended and the phase used are key points? If I don't use water based phases the material is not suspended, it completely precipitates out.
I've realized today that the problem I'm having is that the column is not being packed properly, instead a blockage is created with a little amount of material and then column is not packed , it's just empty but pressure is there due to the blockage.
Thanks!
Aida
Slurry ratios are VERY important indeed.
5u particles in a ~200 micron cap is fine (not ideal, but I know they work as I have done it before), but I have no idea what you are doing so it may or may not be wise to attempt. Back in the early 1990's we used to use 230 - 560 micron columns with 5u particles for nano-LC applications. These were mostly for LC/MS applications... when this type of chromatography on narrow bore and smaller columns was somewhat popular. The columns at best showed ~ 25% RSD. Not very useful for scientific work which needs to be reproducible...
I will repeat my earlier advice. I can not provide detailed information in how to pack these columns on this website for free. It took me many years to become proficient at such techniques. The ratios used and the specialized equipment needed to pack such tiny columns are often proprietary at most companies. The best techniques have been learned through decades of experience and training such that commercial columns can be packed and sold which are reliable for clients to use.
If this is an important project which requires reproducible results, then please turn it over to professional company for packing.
We are currently observing a similar learning curve today with the packing of sub 2.5 micron particles into steel narrow bore columns for UHPLC applications. As of this writing, no column vendor has been able to demonstrate excellent batch-to-batch reproducibilty of these columns. It is very difficult to obtain values anywhere near what we can achieve for 3 to 5 micron supports.
Dear Bill,
thanks for your explanation. Unfortunately I cannot ask for a professional packing now as 75% of the experiment has been done with home-packed columns. i just need to get a good WCX column to finish it, but as I told it's being a hard work.
I know you cannot give me all the details you know, I undestand that is an experience of years, but I'm sure you could provide me some clues, numbers, advices, that could help me to solve that bottle-neck.
Thanks!
Aida
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