chloroform bottom layer removal

[faris]

Hi every one, what is the best way to remove a 2 mL bottom chloroform layer (upper is water) with minimum contamination so that my GC chromatogram be clean. I don't want to use drying

[Don Shelly]

A small Teflon separatory funnel has always served me well.

Don

[Don_Hilton]

As long as you do not have to take all of the chloroform layer, you can withdraw the chloroform layer with a pasteur pipette. Let the pipette bulb fully expand as you draw sample in. Lift the pipette out and dispense into the GC vial.

[faris]

Don, what about the contamination form the top layer. do you mean leave the pipette out for a while till the separation of the two layers is complete and then dispense out the lower (chloroform) in a GC vial.

[HW Mueller]

If you do what Don suggested, but withdraw only minute amounts of the upper layer (just enough to get all the chloroform), there should be no sep. problems.

[Don Shelly]

Faris,

Yes. Allow phase separation and stop collection when the meniscus reaches the stopcock.

Don

[Gilson_PLC2020]

Try one of these cartridges - http://www.gilsonuk.com/catalogue/product/itemNo/730714

You just pour the whole lot in and only one phase comes out the bottom. There are different cartridge types depending on which phase you want to extract and different sizes for different volumes.

[faris]

Try one of these cartridges - http://www.gilsonuk.com/catalogue/product/itemNo/730714

You just pour the whole lot in and only one phase comes out the bottom. There are different cartridge types depending on which phase you want to extract and different sizes for different volumes.

Great and thanks for the help

[Don_Hilton]

Remember that if you get a small droplet of water in the pipette, it will float to the top of the chloroform in the pipette. If you are watching what you are doing, you will not dispense it into the GC vial. And even if you do dispense some water into the GC vial, it will float on the top of the chloroform - and the needle draws from down in the vial (or should, unless someone has been playing with the depth settings for the needle) - it will miss the water droplet.

A small droplet of water should find its way to the side of the vial, so it will be out of the way. No more water will work its way into the chloroform layer after the chloroform has already been extracted with water.

If you are worried about picking up water as you place the pipette into the solution, you can expel a bit of air (just a bubble or two) as you put the pipette through the aqueous phase and into the chloroform layer.