In article <199609190156.VAA26871 at gramercy.ios.com>, jgluz at MAIL.MED.CORNELL.EDU writes:
|> Folks--I've got crystals that I tried mounting in capillary tubes (I've
|> never done this before, by the way). I had the capillary attached to a
|> syringe. I sucked up a couple of washed crystals in a few ul of solution
|> and tried to dislodge them from the solution (leaving them on the side
|> of the capillary) by moving the plunger back and forth. I did this
|> repeatedly for about three hours without success. There must be a
|> better way! Thanks, luz
who has left you to discover this on your own? usually this is learned under
supervision from a skilled crystallographer.
yes, there is a better way. surface tension is going to keep the crystals
in the drop unless you do something about it. Using a capillary, I know of
two ways of getting the crystal in the capillary. 1) use the capillary as
a syringe or pipette, as you have done. 2) mount the capillary on a brass
pin, then fill it with mother liquor from midway up to the top, then drop
the crystal in. it will (usually) sink to the bottom of the liquid. I
personally prefer the second method.
in either case, you then have to remove the excess mother liquor while leaving
the crystal in place. you can do this with either a very thin capillary
pipette or with a filter paper wick. I use a hand-pulled micropipette
attached to a cutomized 0.5 ml syringe; a DNA sequence loading pipette should
also work well. when the bulk of the liquid is gone, i do touch-up with a
filter paper wick. If you don't want to make your own micropipettes or wicks,
look through the Hampton Research catalog, http://www.hamptonresearch.com .
if you venture into cryocrystallography, the need for the capillary disappears.
you pick the crystal up from a drop in a small nylon loop. very simple; the
catch is that you have to experiment to find a suitable cryoprotectant.
=======================================================================
"anyone who's spent a winter in Sweden deserves a full summer
to make up the vitamin D deficiency" - Peter Dunten
=======================================================================
Dave Schuller
modern man in a post-modern world
University of California-Irvine
schuller at uci.edu
