On Tue, 23 Oct 2001, Ernst Witter wrote:

> william anderson wrote:
>
> > Hi Tim,
> >
> > We also just replaced a filament on our Delta C, and we also observed
> > reduced sensitivity....  Has anyone else recently replace any
> > filaments lately and observed any reduction in sensitivity?
> >
> > Thanks,
> >
> > Bill
> >
>
> As it happens, we recently experienced the same on our Delta Plus. Does
> anybody have a suggestion as to what may be the cause?. Does the emission
> pot have to be adjusted?

        I think so, see below ...

> We re-tuned and noted that the we had to increase extraction by about 20%
> for max signal, but sensitivity is still about 30% lower than before.
>
> Ernst
>
> ----------------------------------------------------
> Dr. E. Witter
> Department of Soil Sciences
> Box 7014
> Swedish University of Agricultural Sciences (SLU)
> 75007 Uppsala
> Sweden
>
> Tel +46 18 671237
> Fax +46 18 672795
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>


Dear all,

we observe similar problems from time to time (I'm on a delta C
GC/C-System). Usually the reason is that the filament is not mounted
exactly in horizontal position in its housing. I guess that's what Ernst
means by "adjustment of the emission pot". Minimum deviations from the
correct position are sufficient to ruin your signal intensity, and it may
take a few minutes for your eyes to see. Mostly this happens when repaired
filaments are used. You *can* carefully try to correct the position, but I
would not recommend this. Better get a new filament and have very close
look at it.

Best ...

--
        Uli Flenker

        Institute of Biochemistry
        German Sport University Cologne
        Carl-Diem-Weg 6
        50933 Cologne

        Phone 0049/221/4982-493