[Retorix]

I'm running flash chromatography with a (quite large) Column with a fritted disc. While doing the separation, I'm getting quite a bit of 'pooling' of the solvent system going on between the frit and the stopcock. I'm just wondering if this is normal. It seems like it could be an issue for achieving good separation. I have asked the grad students I am working with but they have always just used a cotton swab in a non-fritted column (where this apparently didn't happen) and are unfamiliar with this new lab equipment. One of them said that they just weren't going to use this piece of equipment again and told me that I shouldn't either. I have attempted to find the answer but no website seems to mention this, which leads me to believe it is probably just a part of the normal operating procedure. I would appreciate any thoughts you guys have on this topic. Thanks.

[Dan]

Ha, yeah, this is why I hate fritted columns. You have to reduce your flow rate to prevent pooling, the narrower the spout, the slower you have to be. For large columns, the high column width to spout width ratio means pooling is a problem even at at appropriate flow rates. It tends not to be a big problem with the smaller columns.

I did once try to hook up a makeshift air intake with a long hypodermic needle bent into a hairpin and the sharp end inserted into the space between the tap and the frit. It stops the pooling, but tends to make a mess - I didn't pursue it, I just stopped using them (at least the large ones).