08-05-04 16:17
No 523807
forgive me if this is redundant, but i've looked previously, and now again and can't seem to confirm my suspicion. when checking the ph of a water/xylene mixture, obviosly the water is on the bottom. if i remember correctly in high school they said to wet the ph papar and dip it into the np? this sounds wrong.....
how do i measure the aqueus layer through the np? do i have to empty it out and check then throw back into my sep. funnel?
thx, just about to work up my first (hopefully) success!
(Stranger)
08-05-04 17:45
No 523819
You might use a nice pipette, dip it right through the nonpolar layer, and draw out a sample.
If you are extracting something, you might just wait until you have basified it properly before adding nonpolar.
It's good to bee back! Don't trust your computer!!
(Hive Bee)
08-05-04 18:00
No 523823
SWIM's just about to base my post rxn liquid. after basing the xylene should contain 1-1.5g meth. so i suppose then that SWIM would just drain some of the aqueuos layer from the separatory funnel and check it.
thx
(Newbee)
08-05-04 22:03
No 523855
If you are doing an extraction or wash with a separatory funnel, just touch the stopper of the flask right after shaking to the pH paper (or indicator) and it should show you pH.
(Hive Bee)
08-07-04 15:38
No 524055
Swip uses a 20ml syringe to get a PH sample beneath the non-polar solvent (meth base)
Ask no question's, and i will tell no lies.
(Hive Bee)
08-08-04 02:51
No 524176
A syringe works well. Use thin plastic extender tubing and/or glass capillary tubes to reach the aqueous layer. If working with larger volumes, just tap off a small volume, measure, then pour back in. Its all about relative mechanical loss...
TIP - when lowering the syringe through the NP towards the aqueous, it will 'swallow' some NP up the tip. To overcome this, draw up the syringe a little before lowering so that when it is in the aqueous, you can squeeze the syringe to clear it. Then suck up the aqueous.