Dave,

I experienced leaky Labco vials at 90°C, but never (knock on wood) at 40°C 
for waters. I was told by a few folks that if the Labco vials are stuck in 
the top of the aluminum heated block then you have an older model block 
that needs to be bored out a bit more so that the caps are loose. If the 
caps are stuck in the top they are more likely to vibrate open. I don't 
know if this is true, but sounds legitimate. I don't run carbonates at 90°C 
anymore for a variety of problems, including leaky Labco caps. I wish there 
was a 3.5ml flat-bottomed vial with threads that are better than the Labco 
ones, but I have not found any.

Question:
If I want to re-use my Labco vials for water (no H3PO4 acid), what septa 
have others reordered?

Toti.




At 05:00 AM 9/7/2005, Dave Mattey wrote:
>We recently experienced a problem with leaking septa on labco vials using
>our GV Multiflow system. It came to light  when some water samples returned
>to us in pre-flushed vials had partially evaporated away.
>
>The problem has been traced to the temperature at which the vials are
>flushed - when the heater block is at 90°C there is no problem; I now
>realise the batches of leaking vials were flushed at 40°C and the needle has
>obviously (hindsight is a wonderful thing) punched a plug of rubber leaving
>a pinhole in the septum, which is harder and less pliable at 40°C.
>
>We mainly run carbonates and some DIC where the vials are flushed at 90°C
>and have not had any problem apart from the two recent batches flushed at
>the lower temperature. As we are about to start running 18O on water by CO2
>equilibration where flushing will regularly take place at 40°C there is
>obvious cause for concern here!
>
>Has anyone else noticed this as a general problem?  I wonder if it could be
>a local problem with the needle or with the batch of elastomer used to make
>the Labco septa? Any input on this gratefully received.
>
>Best wishes
>
>Dave Mattey

Toti Larson Ph.D.
Los Alamos National Laboratory
Earth and Environmental Sciences                505.667.9894 (lab)
Los Alamos, New Mexico 87545