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Carbon and Nitrogen working standards for EA and TOC analysis

The working standards we currently use are:

Sucrose and KHP for d13C on the TOC analyzer and the EA.

Glycine (from Aldrich) for d13C and d15N (referred to as "Glycine Low")

Glycine (from Aldrich) spiked with 2-13C-glycine and 15N-glycine (both also from Aldrich) for d13C and d15N. (referred to as "Glycine Mid")

Glycine (from Aldrich) spiked with more  2-13C-glycine and 15N-glycine (both also from Aldrich) for d13C and d15N. (referred to as "Glycine High")

NIST 2710, Montana soil for d13C of low wt %C samples

NIST 2711, Montana soil for d13C of low wt %C samples

 

Working Standard d13C ( vs VPDB) wt. % C   d15N ( vs air) wt. %N
Glycine Low -39.64 31.58 1.35 18.42
Glycine Mid -8.36 31.58 27.9 18.42
Glycine High 15.67 31.58 51.8 18.42
KHP -24.86 47.01 n/a n/a
IAEA-C-6 sucrose -10.23 42.08 n/a n/a
NIST 2710 -24.74 3.01 5.14 0.30
NIST 2711 -16.91 1.73 7.55 0.13

Carbon calibrations for the glycine and NIST working standards were performed on Sept 13-14 using USGS 40, USGS 41, NBS 18, and NBS 19. The KHP and sucrose carbon standards were calibrated with USGS 40 and USGS 41. Nitrogen numbers for the NIST standard were provided by Rick Doucette at NAU CPSIL. All other nitrogen numbers were measured with USGS 40, USGS 41, and IAEA-N-2.

Note that the international standards that were used to calibrate these working standards have a standard deviation of 0.1 . Although we report our numbers with two digits past the decimal, the accuracy of the final number for any measurement made in the lab cannot be known to within better than +/- 0.2 (+/- 2s) of the actual value.

 

Page last updated: Sept 15, 2006

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