Bill Melchior, NCTR/FDA
WMELCHIOR at NTET.NCTR.FDA.GOV
Fri Oct 9 08:33:50 EST 1992
>Pycnometers are devices which allow precise determinations of
>Does anyone have any knowledge or experience with these?
>There are liquid displacement type instruments and air/gas
I assume you want to measure *density* rather than volume. How you do it
depends on what, why, and how often.
I haven't used a real pycnometer for many years. I have used the classical
glass bulb with capillary stopper -- my recollection is that it worked fine
but was tedious and of course required large volumes. I also did a little
work with one of the electronic units (vibrating tube filled with liquid)
-- I remember having problems with the calibration. If you have many
samples of adequate volume, this would be the easiest, but prepared to
spend both $$ and time in calibration. (As stated, these experiences were
20-30 yrs ago; perhaps the electronic units are easier to use now.
Comments from other users are welcome.)
What I currently do for checking CsCl solutions is to use a siliconized 100
microliter glass capillary pipet, weighed with and without the solution.
I figure it's good to a fraction of a percent. It's definitely easier than
using a refractometer, and non-destructive.
The opinions stated are mine, not those of NCTR or its sponsoring organizations.
Bill Melchior || OMNISCIENCE
National Center for Toxicological Research || Knowing what
Jefferson, AR 72079 || thou knowest not
(501) 543-7206 || is in a sense
WMELCHIOR at NTDOC.NCTR.FDA.GOV || from Grooks, Piet Hein
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