Dear Len

As producer of reagent and capsules for EA we are obliged to supply
quartz tubes also.
So we get a big experience in that field!
The quartz cracking depend on level of Na and K contained in quartz as
raw material and the price of quartz also.
Due to the number of tubee we bought you can imagine that many
manufacturer want to supply us
pouching of course pressure on price. For CE instrument quartz tube
18mmx45, glassblower manpower is quite nothing
so if you want to decrease price you have to offer quartz with
impurities. This is particularly the case with quartz coming from UK
the price is very low but the quality is poor and you get a cracking
each time you cool down.

Na and K is also a problems when you analyze vegetal and food for
protein with big sample size. These elements contain in the ash samples
work as catalyst creating a crystallization of amorphous structure of
quartz tube. In that case the only solution is to use a metallic tube
unfortunatly not compatible with
Chomium oxyde and cobaltous oxyde reagent for CHN determination

Since we produce and supply consumables for EA we decided to supply
highest quartz tube of course at higher price!...
To justify this price difference to your purchase department just make a
calculation on the catalyst and reagent cost lost when the tube brake!



Sincères salutations/Best Regards


Laurent Bertal

Gérant / Manager

Courtage Analyes Services
14 rue des Mouettes
76130 Mont Saint Aignan / France
Tel:+33 2 35 07 60 00 / Fax:+33 2 35 70 64 39
e-mail: [log in to unmask]
http://www.onlinecas.com



Wassenaar,Len [NHRC] a écrit :
> After cooling and cracking another new quartz reactor column on the C+N
> EA I am wondering if anyone has instead tried using thicker walled
> ceramic columns normally used for pyrolysis?  Seems to me these are far
> more robust and could be easily cleaned out and reused without the
> filthy mess left by shattered qtz reactors? 
>
> Anyone tested this? Pros, Cons?  
>
> Len   
>
>
> Leonard I. Wassenaar, Ph.D.
> Stable Isotope Hydrology and Ecology Laboratory
> Environment Canada
> 11 Innovation Blvd.
> Saskatoon, SK
> Canada S7N 3H5
> tel (306) 975-5747
> fax (306) 975-5143
>
>