forgive me if this is redundant, but i've...

[superman]

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!

[yei]

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.

[superman]

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

[biffman]

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.

[p2e3r4f5e6c7t8]

Swip uses a 20ml syringe to get a PH sample beneath the non-polar solvent (meth base)

[biotechdude]

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.