I can relate to the unsteady hand issue, once a week I take a strong dose of caffeine and then try to work in the lab :lol:
A few basic separatory funnel tips:
• Turning the stopcock the wrong direction can slowly loosen the nut that tightens it. For the most part, unless trying to get that last tiny drop, its best to turn it clockwise so any drag on the nut isnt loosening the nut.
• The glass stoppers, you'll notice, are designed just right to hold between the index and middle fingers while you work. This lets you avoid setting it down. If you would rather set it down, have a designated clean spot just for that. I use a petri dish or a watch glass.
• When your ready to isolate the top layer, drain the bottom layer and then pour the top layer out of the top of the funnel. This helps greatly in not contaminating it with droplets from the bottom layer.
• When your salting out alkaloid in a sep funnel, after adding the aliquot of acid and mixing, partially lift the stopper and turn the stopcock 180° quickly 3 or 4 times to wash old droplets out of the stem [catch the washings in a little beaker or shotglass] then you can use a tiny slice of a pH paper held with tweezers and just barely tap it against the last fraction of a drop hanging on the tip of the stem. This is a very convenient and cheap way to get readings on pH after each addition of acid.
• If your stopper or stopcock is the ground glass type remember that strong lye, or prolonged lye contact can fuse the glass pieces together.
• When you get your funnel fill it with water, fit the stopper into it, turn it upside down, place it in a small box on top of a piece of paper so the stem is pointed up and its own weight is holding the stopper in place, open the stopcock and watch for leaks around the stopper, if nothing leaks come back after 15 minutes and look again. When I found a set of 500 and 1000 ml sep funnels from china for less than the usual price of the 500 alone I got them not convinced they would be high quality. They were much better than I expected except the ground joint on the 1000 is off by just enough to eventually let a drop or two leak out. This could be an unpleasant surprise when working with acids or bases so its best to find out how prone your funnel is to leaking, and then never assume it cant leak. Lye and eye may rhyme, but thats where the connection should end.
• Dont leave the funnel drying on the counter when relatives or children are there, I just lost a 70 year old 500 ml volumetric flask that way :lol: