I have run thousands of GFF and GFC filters in our CE NA1500. Best 
advice I can give you is,

-Run 25mm filters loaded into 9x10 tin capsules - some people cut the 
filters and put the bits in the capsule, I fold them in 1/2, 1/4, then 
1/2 the 1/4 and stuff into a 9x10 with the capsule in a holder, squish 
to make a pill shape.
-combust at 1020C
-copper at 650C
-use inserts (one time use, difficult to ash) place a 1 cm of qtz wool 
at the bottom or you could use closed bottom inserts or SS inserts, I 
prefer the qtz.
-run only 20 unknowns, surrounded by conditioners, blanks, and 
standards, any more will cause drift and back flow issues
-use a zero blank carousel with the big hole drum that only allows for 
31 drops.
-I use a 4m column at 60C, He flow at 65ml/min, 10ml O2 loop, all 
pressures set a 100kpa
-determine your dilution, I group by expected yield

If you cannot do the above, you can compromise,
-a shorter column will work provided you can get enough separation 
between peaks which sounds like part of your problem.
-You can load into 5x9 capsules, but better with 9x10.
-If running 45mm, you will need to cut them and run reps and combine. 
hard to fit and combust many 45mm filters.

My thoughts on this,

David


On 4/12/2017 4:08 AM, Sofia Goncalves wrote:
> Dear Isogeochem members,
>   
> We are analysing some difficult samples of POMs for d15N and d13C on our EA 2000 IRMS Delta V Advantage. These samples are colleted and analyzed on filters and have a high C/N.
>
> Some of these samples gives peaks with strange shape and integration. The separation is not good either.
>
> The analytical conditions are as follows:
> - carrier flow 90ml/min
> - oxygen flow: 200ml/min
> - reference flow: 200ml/min
> - ox. reactor: 1020 Celsius
> - red. reactor: 650 C
> - oven: 45 C
>
> Could anyone help me improve this type of analysis?
>
> Thank you very much.
>
> Best regards,
>
> Sofia
> .
>


-- 
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