The absolute abundance of the nitrogen isotopes in the atmosphere and compressed gas from various sources
Abstract
The absolute abundance of the isotopes in atmospheric and commercial compressed N 2 from various sources has been determined. Nitrogen gas standards, prepared by mixing separated nitrogen isotopes in the form of (NH 4) 2SO 4 solutions, were employed to calibrate two 60° sector mass spectrometers. As a result, the absolute ratio of N 14/N 15 in atmospheric nitrogen was found to be 272.0 ± 0.3 Small variations from this value were found for commercial compressed gas. The mass spectrometric procedure used in determining the N 229+/N 228+ ratio allowed for detection of differences to 1 part in 3500. However, the absolute accuracy of the abundance measurements was limited to 1 part in 1000 because of the semi-micro Kjedahl distillation employed to determine the amount of (NH 4) 2SO 4 present in the solutions of the separated isotopes. In these measurements, instrumental background played a very significant role. A reliable method of correcting the observed N 229/N 228+ ratio for the contribution of the background at these mass position was developed.
- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- September 1958
- DOI:
- 10.1016/0016-7037(58)90082-6
- Bibcode:
- 1958GeCoA..14..234J