Print

Print


Dear Anita,


Are you looking for inorganic (lab) standards to preserve IAEA-N1 and IAEA-N2 (both ammonium sulphates) or are you looking for organic (lab) standards?

If it is the former you after you could purchase USGS25 and USGS26 (both ammonium sulphates too) with d15N values of -30.41 and +53.75 per mil, respectively.

If you require (lab) standards for scale calibration and quality control of organic samples I would recommend getting started by purchasing USGS40 and USGS41 (both glutamate) with d15N values of -4.52 and +45.57 per mil, respectively.  Both these materials are recognised reference materials so you could use these to determine scale calibrated d15N values of lab standards, for which amino acids (as suggested by Stan) would be a good choice since their chemical make-up (in particular their C/N ratio) is a good match for most organic materials.

As also mentioned by Stan, some AAs are a pain to weigh out (either lumpy or electrostatically charged like the dickens). In these instances, we prepare aqueous stock solution which we dilute to end up with solutions where for example 10 microL contain 0.4 mg.  In line with the desired sample weight, we dispense small volumes of the dilution into tin capsules sitting in a well-plate made of solid metal.  This metal well-plate is eventually placed in a tray filled with liquid N2 to flash-freeze the samples and the frozen well-plate is subsequently placed in a freeze dryer.  This procedure yields standards of highly reproducible sample weight (and, hence, N2 and CO2 peaks).


Best wishes,

Wolfram


From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Anita Aerts-Bijma
Sent: 16 September 2013 12:23
To: [log in to unmask]
Subject: [ISOGEOCHEM] 15N labstandard

Dear colleagues,
in order to preserve the IAEA standards N1 and N2 we like to have  labstandards with  delta 15 values of 0  and around 20 . The zero value doesn't appear to be a problem, but a material with the higher value we can't find until now.
Does anyone of you find a readily available material with a d15N of approx 20?
Thanks,
--

Anita Aerts-Bijma
Centre for Isotope Research, University of Groningen.

Centrum voor IsotopenOnderzoek (CIO), Rijksuniversiteit Groningen
Nijenborgh 4, 9747 AG Groningen, Netherlands
tel +31-50-3634716 fax +31-50-3634738
http://www.rug.nl/cio<%20http:/www.rug.nl/cio>



________________________________________________________



This email is from the James Hutton Institute, however the views

expressed by the sender are not necessarily the views of the James Hutton

Institute and its subsidiaries. This email and any attachments are confidential and 

are intended solely for the use of the recipient(s) to whom they are addressed.

If you are not the intended recipient, you should not read, copy, disclose or rely on 

any information contained in this email, and we would ask you to contact the 

sender immediately and delete the email from your system.  Although the James 

Hutton Institute has taken reasonable precautions to ensure no viruses are present 

in this email, neither the Institute nor the sender accepts any responsibility for any 

viruses, and it is your responsibility to scan the email and any attachments.



The James Hutton Institute is a Scottish charitable company limited by guarantee.

Registered in Scotland No. SC374831

Registered Office: The James Hutton Institute, Invergowrie Dundee DD2 5DA. 

Charity No. SC041796