You can put a little bit quartz wool at the bottom of these insert before you place them into combusiton reactor. These inserts certainly can be reused for a few times.  You always can add something, say V2O5 to improve the combusiton of your samples if this is your concern.

River He

--- On Wed, 11/18/09, Yanhua Feng <[log in to unmask]> wrote:

> From: Yanhua Feng <[log in to unmask]>
> Subject: [ISOGEOCHEM] insert tube for ash removal
> To: [log in to unmask]
> Received: Wednesday, November 18, 2009, 5:58 PM
> Dear all,
>    We have a EuroVector EA 3000 for CN
> analysis. I am always concerned 
> about incomplete combustion after some ash piled in the
> combustion tube. 
> especially with acid fumigation samples, I use two silver
> capsules for each 
> sample. 
>   I heard that there is a way to remove the ash with
> an insert tube. I am 
> wondering if anyone has experience on that. We have a few
> tubes in the lab. I 
> think that they are insert tubes. 22cm long, transparent
> glass, thin wall, 4 
> slots on one end. But there is nothing to tell me how to
> use them. the end 
> with slots should be on the top or the bottom. etc. 
>    I could also buy some new ones if someone
> can tell me which kind fit my 
> instrument. etc. 
>    appreciate any suggestion. 
> Yanhua Feng
> New Mexico State University
> Plant & Environmental Sciences
> Las Cruces, NM 88003

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