On Wed, 10 Apr 1996, Neil S. Summer wrote:

> Hi Rainer,
> 
> There is an alternative..... an In-line Flourine generator. Such a
> generator  has been working for years in Dave Wenner's Lab at UGA. I've
> 
> Potassium-Nickle-Flouride compound is placed in a  nickle cylinder. The
> vessel is sealed, valved etc., The cylinder is routinely charged off-line
> with Flourine gas (in a fume hood). The compound absorbs Flourine at
> 210-280C.  At room temperature the gas is fixed.  On-line heating to a
> little over 300C releases Flourine for normal Silicate line operations!
> One charge lasts 4-6 months,  the small Flourine gas cylinder (supply)
> lasts approx 2 years.

Doug Rumble published details of a system for sulphur isotope analysis
on SF6 using a similar K-Ni-F compund to generate/resorb fluorine in G.C.A. 
vol57, 4499-4512.

The laser-fluorination system at RHUL (Mattey and Macpherson, Chem.
Geol. (Isotope Section) 105, 305-318) employed ClF3 and a hot KBr + liquid
N2 trap to get any rouge F2 generated during the laser heating. We did
notice some corrosion of s.s. ports where fresh and waste reagant were
imported/exported. This diminished both the precision and accuracy
of the system. 

Also, CO2 ice formed by combustion with graphite occasionally
had an orange colouration which we attributed to trace amounts of
bromine swept through the N2 trap by the flow of O2 to the graphite.
The effect was most intense in two situations. First, it could occur when
large samples were analysed, probably due to a greater oxygen flux through
the N2 trap. And second, it was often observed during olivine analysis.
This may be due to the high melting temperature of olivine causing 
intensified reagent dissotiation during fluorination, and hence greater
Br production during F2 passivation. However background scans of this
CO2 revealed no obvious peaks at masses for Br gas or F-O-C bearing
compounds.


All the best,

Colin.

      __________________________________________________________
       Colin Macpherson              [log in to unmask]   
       Dept. of Geological Sciences  University of Saskatchewan 
       Tel: (306) 966 5691	     Fax: (306) 955 8593
      __________________________________________________________