A final point to clarify the misunderstanding about the inner wall coating on the Labco
Exetainers.

>
>
> (5) I fail to see as to why one would need a desactivated/coated
> glass surface for breath tests that are only interested in measuring
> CO2. The moisture (water) with its dissolved CO2 should stay
> equilibrated with the free CO2 in breath since you don't
> change temperature or partial pressure (Henry's Law) when collecting
> and storing your samples. So, whether the water clings to the glass
> surface or runs down, collecting at the bottom of the tube, shouldn't
> make a difference.
>

As originally stated, these containers have been optimised for 13C breath testing. The
coating of the glass surface is to serve as a visual aid to the person undertaking the
breath test. Breath is put into the tube by a person blowing through a straw. This
displaces the air and at the same time deposits a vapour mist on the wall to indicate
to the user that tube has in fact been filled with sample (so as to avoid Murphy's
law).

Steve Brookes