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
Courriel / E-mail: [log in to unmask]
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.
>
|