> I am using IAEA-NO3 (+4.7 permil KNO3)as a standard for an EA-DeltaPlus. If
> I use this the N peak gets quite broad (80 seconds) compared to a plant
> sample (55 seconds) and it is tailing much more. If I use IAEA-N1 (+0.4
> permil (NH4)2SO4) I also get a nice peak of 55 seconds. Earlier on I also
> had a nice peak for IAEA-NO3, and now it suddenly has changed, also the
> delta value is changed by ± 0.8 permil. I checked all the reactors and
> traps and this seems OK.
> As there is no CO2 peak for KNO3 I can't check on this. I added a little
> carbon to the IAEA-NO3 and then the peak looks a lot better. So the cause
> may be a too slow burning of the KNO3. Does anyone have experience with this?
> Als suggestions are welcome.
Funny you should write this... today I found exactly the same with
NaNO3 and KNO3, poor recovery of N after combustion, but if some
sugar is added things look an awful lot better and recoveries of N
are what I expected.... and the d15N values were quite different...
but the Mg(NO3)2 was the same irrespective of whether I added
Expanding the analysis window on the Europa 2020 did not improve
things that much.
My two bits.
Scottish Crop Research Institute
Tel No: (44) 1382 562731 ext 3732
Fax No: (44) 1382 562426