It's either that (NO formation and exhausted reduction tube) or your machine
has drifted away from the original tune parameters so cup 1 now samples the
flank of either m/z 28 or m/z 29 and cup 3 collecting predominantly m/z 29.

Cheers,

Wolfram


> -----Original Message-----
> From: Stable Isotope Geochemistry 
> [mailto:[log in to unmask]] On Behalf Of Kim Baublys
> Sent: 04 October 2005 05:51
> To: [log in to unmask]
> Subject: Puzzle: SIRMS of N in RNA
> 
> 
> Hi Everyone,
> 
> Does anyone have experience in doing nitrogen on RNA or DNA?  
> I have run 
> DNA samples for carbon with no problems but the Nitrogen is proving 
> problematic and I freely admit that I haven't a clue and that 
> I am hoping 
> that someone can provide a 'quick fix' :)
> 
> I am using an Isoprime with a Carlo Erba EA.  The problem is 
> that my 28 
> peak was only 5X10-10 Amps while the detector for mass 30 was 
> swamped and 
> there still appears to be mass 30 coming from the EA.  Never 
> having run RNA 
> for nitrogen is it possible that the combustion was not 
> complete and that I 
> am getting NO?  What other species could it be?  I wouldn't 
> have thought it 
> would be hard to combust properly.  (I will be checking my 
> reduction tube 
> tomorrow morning just in case something has gone wrong there)
> 
> Any suggestions on the analysis would be appreciated plus 
> recommendations 
> on which papers to read.
> 
> Thanks
> Kim
> 
> 
> 
> Kim Baublys
> Stable Isotope Laboratories
> Department Of Earth Sciences
> University of Queensland 4072
> Australia
> 
> Ph:   +61 7 3365 1131
> Fax: +61 7 3365 1277
> http://www.uq.edu.au/geochem/
>