Chromatography Forum

The EPA solid waste methods (3550C for example), say you should purify sodium sulfate by heating in a shallow tray at 400C for four hours, or cleaning it with DCM.

I've got a tiny little muffle furnace to work with, so unless I get real creative about how I interpret "shallow tray" (250ml beaker filled to the top? ) it's hard to clean enough - and we only use a couple hundred grams a day.

Anyone have a better way to do this that doesn't require dropping thousands on an oven just for this purpose? I haven't really figured out a good way to clean it with DCM that doesn't waste tons of solvent.

I did consider taking the column out of one of my GCs and using it as the oven...

I'd use the 250ml beaker in your existing oven.

Not atypical for any official method to be vague, like one could interpret shallow in many ways. For example, my above-ground swimming pool is only four feet, so it's shallow.

I assume that you're trying to drive the water out of the sodium sulfate, so it could be used to pull some water out of an organic solvent in the EPA procedure.

We used sodium sulfate granules for similar purpose in non-regulated procedures, and we used it directly from the jar.

The point is to destroy any organics in addition to just removing water. The shallow tray is to ensure that it is heated through to 400 degrees for much of the 4 hours. The same result could be obtained by heating it for a longer period, such as overnight. We used stainless steel beakers rather than Pyrex, less chance of breakage.

Steve Reimer wrote:
The point is to destroy any organics in addition to just removing water. The shallow tray is to ensure that it is heated through to 400 degrees for much of the 4 hours. The same result could be obtained by heating it for a longer period, such as overnight. We used stainless steel beakers rather than Pyrex, less chance of breakage.

We normally heat ours overnight when using the oven, but when we have a bad problem with hydrocarbon contamination of the sodium sulfate we put it in a Soxhlet and reflux it with Methylene Chloride overnight, that way a couple hundred mls of solvent can clean more material. We don't us a thimble, just pack the bottom with glass wool and put the sodium sulfate on top, that way you get more loaded in the Soxhlet and you don't worry about the thimbles being contaminated as some can be.

I'd make a little rack to hold a few evap. dishes or watch glasses, then load that furnace up! Go vertical.