Dear Clemente,

Apologies for asking the obvious questions first: where is your cold trap (at what point in the interface) and what are the dimensions of the trapping loop?

Assuming everything is ok with the set-up of your cold trap, are the AA samples you are analyzing very abundant in one (or more) particular amino acid(s); an amino acid you might not be interested in?

Example: collagen digest samples yield huge Gly peaks.  When I was carrying out CSIA of bone collagen digests we were mostly interested in Pro and Hyp so I heart-cut the Gly peak from the chromatogram so it would not enter the combustion interface. This way we could run more analyses before the cold trap became clogged.

Best wishes,


-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Clemente Recio
Sent: 02 March 2015 10:57
To: [log in to unmask]
Subject: [ISOGEOCHEM] N analysis by Isoprime GC-C-IRMS

Dear Colleagues,

We are trying to do N in aminoacids by
GC-combustion using an Isoprime MS coupled to an Agilent GC, and are having difficulties trapping the CO2 before the MS.

I would very much appreciate hearing from any of you with experience in similar work. It is obvious that we are doing something wrong, and I need help to identify our mistakes and sort those out.




ROGAMOS a nuestros usuarios y amigos NO UTILICEN el servicio de CORREOS para enviar sobres y paquetes al Laboratorio. LOS ENVIOS NO SON ENTREGADOS

We kindly request our Users and Friends NOT TO USE THE SPANISH MAIL SERVICE ("CORREOS") for letters and/or parcels addressed to us. SHIPMENTS ARE NOT DELIVERED.

Dr. Clemente Recio
Laboratorio de Isótopos Estables
Edificio Multiusos I+D+i
Univ. de Salamanca
C/ Espejo, 2
Phone: (+34) 923 29 45 00, Ext. 1540 (Automatic Switchboard)
E-mail: [log in to unmask]
Web page:


This email has been scanned for spam and viruses by Proofpoint Essentials cloud email security - visit the following URL to report this email as spam:

Robert Gordon University is the top university for graduate jobs in  the UK HESA 4 July 2013

Robert Gordon University, a Scottish charity registered under charity number SC 013781.

This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender.  Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of Robert Gordon University.  Thank you.