Nitrogen isotope standard

Figure 2.3. Carbon and nitrogen isotope values of human bone collagen at Maya sites in Belize. The value for the modem sample has been corrected for collagen-hair spacing and the Industrial Effect. Boxes represent isotopic means one standard deviation.

The precision of the method is better than 0.2%o (1 SD) at concentrations of nitrate down to 1 p,M, and the nitrogen isotopic differences among various standards and samples are accurately reproduced. For samples with 1 p,M nitrate or more, the blank of the method is less than 10% of the signal size, and various approaches may reduce it further. 

Jensen ML, Nakai N (1962) Sulfur isotope meteorite standards, results and recommendations. In Jensen ML (ed) Biogeochemistry of sulfur isotopes, NSE Symp Vol, p 31 Jia Y (2006) Nitrogen isotope fractionations during progressive metamorphism a case study from the Paleozoic Cooma metasedimentary complex, southeastern Australia, Geochim Cosmochim Acta 70 5201-5214... 

Carbon and hydrogen measurements were made on a Varian MAT 250 triple collecting MS and sulfur and nitrogen on a Nuclide RMS 6-60 dual collecting MS. Atmospheric N, Chicago Pee Dee belemnite, SMOW and Canyon Diablo troilite were used for isotope standard Analytical errors for isotope ratjp measurements were as follows 8 C 0.05 per mil, SD 3 per mil, 5 S 0.4 per mil, 5 N 0.4 per mil, and for elemental analyses, C 0.5%, H l%, S 0.5%, N 0.5%. 

Table 7.6 Internationally accepted stable isotope standards for hydrogen, carbon, oxygen, nitrogen, and sulfur.

Figure 2. Nitrogen isotope abundances in solar system materials upper scale gives absolute ratios lower scale gives relative to the terrestrial AIR standard. Heavy bars show observed ranges light bars show measurement...

Grevesse N, Sauval AJ (1998) Standard solar composition. Space Sci Rev 85 161-174 Guillot T (1999) A comparison of the interiors of Jupiter and Saturn. Planet Space Sci 47 1183-1200 Hashizume K, Marty B, Wieler R (1999) Single grain analyses of the nitrogen isotopic composition in the lunar regolith—in search of the solar wind component. Lunar Planet Sci XXX, abstr 1567, Lunar Planet Institute, Houston (CD-ROM)... 

Determining the N-isotopic composition of sedimentary OM requires that N2 gas be prepared from the sample. The gas is then fed into a mass spectrometer for analysis. An excellent, comprehensive review of mass spectrometry, and the various sample preparation techniques that may be used for N-isotope analysis, is given in Owens (1987). Attention here will be confined to some of the more pertinent practical aspects of isotopic analysis with particular reference to the system used at UB. As indicated in the Introduction, the adoption of nitrogen isotopes as a standard technique in the earth and biological sciences was hindered by the time-consuming, off-line preparation techniques that most studies required. A few labs have stuck to the original, wet-chemistry sample preparation, feeling... 

AIR. (atmospheric) air, a standard for nitrogen and chlorine isotopes APCL atmospheric-pressure chemical ionization, also called plasmaspray API. atmospheric-pressure ionization... 

Table 1.7 Worldwide standards in use for the isotopic composition of hydrogen, boron, carbon, nitrogen, oxygen, silidum, sulfur, and chlorine...

Acylcarnitine analysis of dried blood or bile spots is very similar to the analysis of plasma. A small disk (diameter typically 5 mm or less) is punched out of the blood spot and the acylcarnitines extracted by the addition of methanol and known concentrations of isotopically labeled acylcarnitines, which function as internal standards. The extract is dried under a stream of nitrogen, and derivatized by the addition of either n-butanol HC1 or n-methanol HC1. The acylcarnitines are measured as their butyl or methyl esters by MS-MS. The concentrations of the analytes are established by computerized comparison of ion intensities of these analytes to that of the internal standards. 

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