Hi Michael and interested others,
I've run hundreds (the memories flood back) of analyses using serum vials
capped with teflon faced septa. The less expensive rubber septa will
leak.....and apparently degas as well. I usually analysed my water samples
within a month or so of collection. As a test, I have analysed duplicates
as much as a year and a half later with no significant change in d13C
value. For poisoning, I placed a few crystals of HgCl2 in the vial before I
inject the filtered water sample. The crystals eliminate the problem of
spilling or dripping a saturated HgCl2 solution while your out on the
water. Jim Burdett has suggested an even better idea which combines the
best of both worlds. He places a drop or two (?) of saturated HgCl2 in the
vials and allows them to dry into a thin toxic crust. That way the powder
doesn't float around in the dry vial as in my case and you don't have to
carry a nasty solution into the field with you as in the other case.
Fill the vials to the top and cap them. For extraction, tear off the center
disk and push two Lure-lok syringe needles in through the cap forcing clean
nitrogen into the vial. The solution will fill the other syringe which I
also purge with clean, dry nitrogen. Its all pretty quick and easy, and
your sample goes straight into the vacuum line never exposed to atmosphere.
I have used "Wheaton" 20ml serum vials. Catalog #223742, mouth ID = 13mm,
OD = 20mm. Price for 288 is $174.92.
Cap them with Teflon faced gray butyl septa. Catalog #224168. Price for 100
Crimp them down with unlined center disc tear-out aluminum seals. Catalog
#224183-01. Price for 1000 is 48.82.
You'll need a crimper as well. Catalog #224303 for the hand crimper. Price
If you're doing millions of samples, they offer the "Crimpmaster" pneumatic
crimping station for $602.96.
Hope that this helps and good luck,
William P. Patterson
Department of Earth Sciences
204 Heroy Geology Laboratory
Syracuse NY 13244-1070
Email: [log in to unmask]