Hi all!

Do you remove the ash from your column between runs?  The easiest way to do
this from our experience is to insert into the top of the combustion column
a short length of quartz tubing, slightly shorter than the distance from the
top of the chemicals to the top of the furnace tube, and with an OD just
smaller than the ID of the tubes.  After each run lift the carousel off and
extract the quartz liner with tweezers (carefully!  It's hot.) and knock the
ash and uncombusted material out.  This should extend the life of your
columns dramatically.  Most of the degradation we see in chromatography and
isotopic data is due to the ash blocking the gas path.  On both our EA/IRMS
machines we remove the ash after every run.

Hope this helps someone,

Andrew Tait
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Scottish Universities Research and Reactor Centre
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Phone:  +44 1355 223332
Fax:  +44 1355 229898

----- Original Message -----
From: Ravi Bhushan <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, March 25, 1999 1:53 AM
Subject: NC Analyser!


> Dear Friends,
>
> We have a FISONS NA1500 NC analyser. We are using it frequently for the
> analyses of marine sediments for carbon and nitrogen content. Fisons
> principals claim that one can run upto ~200 samples per column filling but
> the best I have been able to run is not more than 120 samples averaging
> ~100 samples per filling, which is on a very lower side realising the
> cost of each filling. Can anyone suggest some alternative. Also if anyone
> can provide me the following information :
>
> 1) We are maintaining sample size of ~10mg, but it sometimes becomes
> difficult for samples with very low carbon and nitrogen content. Does the
> sample size controls the no of runs per filling.
>
> 2) Are there any standards available for analyses of marine sediments with
> different concs. of carbon and nitrogen content.
>
> 3) Does the acidified samples (samples treated by HCl for removal of
> carbonate fraction, HCl fumed filters etc) has any effect on the life of
> the column filling. We have found while using acid treated samples that
> column gets consumed very fast, sometimes just after 25-30 runs. Any
> solution for this problem.
>
> I shall be grateful if someone could give me feedback on this.
>
> Thanking you in anticipation
>
> Regards
>
> Ravi
>
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