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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