Does anyone have any experience using a magnetic stirrer in an extraction? I'm worried that using one might produce unwanted emulsions.

It works wonderfully!

There are some mixing magnets that have weird shapes specifically to increase emulsions, but normal ones are fine. The magnetic mixer should have speed control, so you start it slow and raise gradually as you see the vortex forming. Ive had best results when leaving it for long, but when you can still see some tiny bit of the solvent layer on top as it mixes. Once I left it for a whole day on max speed where both layers mixed completely (and probably some air involved too), and it formed a very persisting emulsion, so just avoid that and you should be fine.

Hello endless, what material is your stirring bar made of/coated with?

ferritic stainless steel would work, i should think

How did you defeat the emulsion?

Just buy some Teflon coated bars from eBay they are perfect.

yeah PTFE bars are good.

The emulsion was dealt with by salting with acidic solution a few times, basing the solution and extracting again

I was looking into these devices some more and noticed that "heat control accuracy" is expressed in K, e.g. 10 +/- K, 20 +/- K...

What does this K stand for? I can't imagine it standing for Kelvin as I looked up what 10 Kelvin means in °C...

Any clarification would be most appreciated

PLUR

Could you please link us to the specs of the devices you're looking?

10+/- K could very well mean Kelvin. 10+/- K is the same as 10+/- Celsius, even though that is a huge error. Obviously 10+/- K is very different from 10 K

http://www.ika.com/owa/i...mp;iSubgroup=1&iCS=1

If the heat control accuracy is more or less 20 °C such a device would be quite worthless without the optional temperature sensor which increases heat control accuracy to 1 +/- K...

The heat control accuracy of my cousin's kitchen oven (analog adjustment) is about 15 °C (we measured this with his super accurate thermometer while converting sodium bicarb into sodium carb...)...

Your link says that this hotplate stirrer (which are considerably more expensive than just stirrers) and is 1+/- K accurate, which is the same as saying 1+/- C accurate. Where does it say that it is 10+/- K ?

BTW, it looks like a decent hotplate stirrer.

It's heating control accuracy is 1 K when using an external (optional, expensive) thermometer that plugs into the device, it's 20 K using the device's control knob...

Digital models have 10 K accuracy built-in, so they too "need" the external thermometer for adequate accuracy...

I'll look into the accuracy of hotplates without stirrer for comparative reasons, perhaps having two separate devices for both heating and stirring would be more efficient...

But where does it say that in the product description?

Anyway, what are we discussing anyway? Accuracy does not really matter; you have the heat knob and the more you turn it the hotter the plate gets. Keep it in a position until liquid you plan on stirring gets to the desired temperature. If hotter/colder than desired, dial the knob down or up a bit. Monitor temperature with any cheap thermometer. That's how labs do it.

SERIOUS WARNING: If you do actually plan on using a hotplate stirrer, make sure you do not use plastic containers. Hotplates can get surprisingly hot (especially if you are not keeping an eye on them) and you will end up with melted plastic and whatever liquids you are heating all over the place.

I use nothing but glass and stainless steel... Furthermore, no direct contact between hotplate and extraction vessel would ever be allowed... Something along the lines of stainless steel pot, thin slice of cork on bottom, put glass extraction vessel on cork, fill pot with oil, start heating?

Thanks infundi for your input