Hi Gerry
Make sure you lipid extract the fish tissue otherwise it destroys the chemicals within a few samples and results get worst almost immediatly.  Try running some inorganic first (e.g. pyrite) to confirm that the system is working well.

Gilles

Gilles St-Jean
Chercheur / Research Scientist
Université d'Ottawa / University of Ottawa
Sciences de la Terre / Earth Sciences
140 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
Tel: 1-613-562-5800 xt 6830 (Bureau / Office)
                    xt 6839 (Bureau / Office Lab)
                    xt 6836 (IRMS lab)
Téléc. / Fax: 1-613-562-5192
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Toile / Web: www.isotope.uottawa.ca

 

> -----Message d'origine-----
> De : Stable Isotope Geochemistry 
> [mailto:[log in to unmask]] De la part de Gerard Olack
> Envoyé : 13 janvier 2006 10:01
> À : [log in to unmask]
> Objet : [ISOGEOCHEM] sulfur burning issue
> 
> HI All--
> 
> I switched our EA, Costech ECS 4010, over to sulfur mode 
> (tungstic oxide oxidation column, pre-packed from Costech, 
> teflon tubing, 2m GC column), and can't seem to get the SO2 
> to come out in a single peak.  Organic material, 
> sulfanilamide or ground fish, gives two main peaks--a sharper 
> early one at ~400 sec and another one (or more) broad one 
> around 550 sec.  Both sulfides and sulfates (with added 
> tungstic oxide) only give the latter broad peak(s), 
> regardless of sample size or added organic material.  The 
> early peak is similiar to the what I was getting  the last 
> time I ran sulfur (sulfides, sulfates, some sulfanilamide).
> 
> I've changed the transfer lines a couple of time (now 
> bypassing Costech detector plumbing), cranked the hotplate 
> under our conflo up, have the GC running at 110 (highest temp 
> setting), swapped drying tubes, and have been playing with 
> drop timing and oxygen amounts.  I'll  be swapping the ash 
> collector and having at it again--but I would appreciate any 
> suggestions.  Also are their any particular pitfalls to watch 
> out for when running organic samples?  We're running ~8mg for 
> the fish to get a reasonable signal (or what will be 
> reasonable once we get a fairly clean peak). 
> 
> thanks in advance--
> 
> take care
> 
> gerry
> 
> p.s.  I was playing with PEEK tubing in place of teflon 
> (lower gas permeability than teflon, don't heat gun PEEK).  
> It seemed ok in initial tests last time around, but it was 
> one of the first items that got swapped out this time.  It's 
> more expensive than teflon/PTFE tubing, but it may be a 
> viable option if you require lower gas backgrounds.
>