Standards of known isotopic composition currently in use in the laboratory
For NITROGEN isotopes
For CARBON isotopes
|IAEA-N-2 Ammonium Sulphate δ15N +20.30 ± 0.2||IA-R041 L-Alanine δ13C -23.33 ± 0.10|
|IA-R041 L-Alanine δ15N -5.56 ± 0.14||IAEA-CH-6 Sucrose δ13C -10.45 ± 0.03|
|IA-R001 Wheat flour δ15N +2.55 ± 0.22||IAEA-CH-7 Polyethylene δ13C -32.15 ± 0.05|
|IA-R068 Soy Protein δ15N +0.99 ± 0.07||IA-R006 Cane Sugar δ13C -11.64 ± 0.03|
|IA-R069 Tuna Protein δ15N +11.60 ± 0.09||IA-R001 Wheat flour δ13C -26.43 ± 0.08|
|Sorghum Flour Standard OAS 155N +1.58 ± 0.15||IA-R068 Soy Protein δ13C -25.22 ± 0.02|
|IA-R069 Tuna Protein δ13C -18.88 ± 0.05|
|Sorghum Flour Standard OAS δ13C -13.78 ± 0.17|
An in-house fish standard (δ15N +17.78; δ13C -31.65) is also routinely measured as a mass spectrometry quality control sample and has currently been measured more than 2000 times.
Furthermore, collagen extraction is repeatedly performed on whale bone standard (UB 8968) and mammoth bone standard (UB 33333) and these are measured routinely both for C14 and stable isotopes for quality control purposes.
As the weight of the sample is known, the %C and %N can also be determined if a specific weight of a standard of known %C and %N is also combusted and measured. The standard currently in use to ascertain %element values is Nicotinamide (59.01% carbon and 22.94% nitrogen). The values are then used to calculate C:N ratios which are one of the primary indicators of the degree of preservation of bone collagen and/or contamination by soil organic substances.
The machine uncertainty is reported for δ13C and δ15N. This has been validated by the observed reproducibility of measurements on 10 replicate aliquots of seven different bone samples, which show no additional variability.
The facility has:
- Thermo Delta V (IRMS) for 34S/32S (δ34S) ,18O/16O (δ18O) and 2H/1H (δ2H) Solids & GC-PAL Autosampler for (δ18O) and (δ2H) fluids
- Analytical Precision 2003 with Acid Digester for the 13C/12C (δ13C) and δ18O analysis of carbonates.
- Thermo Finnigan Delta Plus Advantage IRMS & Trace DSQ coupled Trace GC for compound specific isotope analysis (δ13C).
- Isoprime Mass Spectrometer with EA for measurement of 13C/12C and 15N/14N in organic matter.