We use a Multiprep on an Optima (dual inlet) here in Bordeaux and
encountered the same problem of bubble on the bottom of our V-vials. As
the acid didn't reach the sample, there was no reaction and no gas to

It seems we had 2 problems at the time :
- our H3PO4 was too viscous (1.92),
- our vials were not cleaned very well, so the acid didn't spread out
correctly on the glass.

Now, we use H3PO4  with a density of maximum 1.90, we clean our vials
with HNO3, and we don't have bubbles anymore...

Good luck,


tlarson a écrit :

> Folks,
> I am trying to react carbonates using a GV Multiflow (Basically same Idea
> as GasBench as far as I can tell in that the H3PO4 reaction occurs in a
> helium environment and not a vacuum. So both camps are free to
> answer), and
> I noticed that after the H3PO4 was dispensed there was a tiny bubble
> at the
> bottom of my sample vial. This is obviously not a good thing. Has anyone
> experienced similar issues with continuous flow carbonate analysis? Is
> this
> one advantage the running with a vacuum system such as the GV multiprep?
> I am using 1ml Wheaton vials that have a cone-shaped bottom and the H3PO4
> has a sg. of 1.94. What bottom-shaped vials are people using with the
> GasBench or Multiflow? Maybe thats the problem. Reaction temp=90°C
> Thanks in advance,
> Toti.
> Toti Larson Ph.D.
> Los Alamos National Laboratory
> Earth and Environmental Sciences                505.667.9894 (lab)
> Los Alamos, New Mexico 87545            550.667.8006 (office)


Departement de Geologie Oceanographie
Universite Bordeaux I
Avenue des Facultes

Tel : 0 (33) 5 40 00 83 62
Fax : 0 (33) 5 56 84 08 48
E-mail : [log in to unmask]
Web :