We recently had an oxygen leak in our Costech EA. It was in a weld in
the semi-micro loop itself. Do a leak check for oxygen for all three
of the oxygen loops. It might be apparent which if any is leaking.
Also you could waste a little copper and do a few test runs using the
macro oxygen loop and see if that helps. We were getting really poor
combustion when we were having the leak and once I switched to the
macro loop we returned to flash combustion and all was good again.
On Aug 29, 2006, at 2:40 AM, Dr W Meier-Augenstein wrote:
> Dear Allison,
> Purely based on the chromatography (the 28/29/30 peak shortly followed
> by a bear but a 30 peak) I'd say you are looking at NO+.
> The main reason is incomplete reduction but the question is why? One
> possible cause could be a problem with the O2 pulse (too much or an O2
> into the EA) which causes your reduction tube to expire before its
> Another reason would be a problem with the reduction stage such as
> temperature or the copper filling.
> Just to cover all bases, you are happy the water trap isn't spent?
>> -----Original Message-----
>> From: Stable Isotope Geochemistry
>> [mailto:[log in to unmask]] On Behalf Of Allison Burnett
>> Sent: 28 August 2006 17:18
>> To: [log in to unmask]
>> Subject: Unexpected Mass 30 Peak
>> I am currently running sediment samples in tin capsules in an
>> elemental analyzer (Costech ECS 4010) connected through a
>> ConFlo to a MAT 252 Finnigan Mass Spectrometer.
>> After changing out the oxidation and reduction columns in the
>> EA, we are now getting a high mass 30 peak for an unknown
>> reason. I'm assuming the peak is from NO+, but I can't
>> figure out why, or how to fix it.
>> I have included links to two pictures taken by screen capture
>> from the EA software.
>> I apologize about the resolution of these images. The first
>> image is the signal from a blank (a tin capsule with nothing
>> inside of it.) The first two peaks are from the nitrogen
>> standard gas, and the last three peaks are from the carbon
>> dioxide standard gas.
>> The second image is from an Acetanilide sample, also run in
>> tin. I ran several blanks interspersed with the Acetanilide
>> samples, each blank and each Acetanilide sample looked the
>> same as these two images. As before, the first two peaks are
>> the nitrogen standard gas. The third peak is the nitrogen
>> signal from the Acetanilide; although it is hard to see in
>> this image, the mass 30 signal starts out normally, rises and
>> falls with mass 28 and 29. The mass 30 signal then spikes as
>> mass 28 and 29 continue to fall.
>> The fifth peak is the CO2 signal from the Acetanilide; I do
>> realize that my changeover timing is off, and I plan to
>> changeover about 10 or 15 seconds earlier than what is shown
>> in this picture.
>> If anyone has any ideas on what is causing this extremely
>> high mass 30 peak, I would appreciate any knowledge and/or
>> advice you can offer.
>> Thanks for your help,
>> Allison Burnett
>> Master's Student
>> Syracuse University
Jason Curtis, Ph.D.
Stable Isotope Mass Spec Lab manager
Department of Geological Sciences
241 Williamson Hall
University of Florida
Gainesville, FL 32611
[log in to unmask], office 352-392-2296
lab 352-392-3344, fax 352-392-9294