Calibration of an emission spectrometric analyzer measurement of 15N abundances.

GALLEGOS,E., BERBEGLIA,Y. AND OSTERA,H.A.

Punta del Este

Simposio; V South American Symposium on Isotope Geology; 2006

Fac. de Ciencias y Fac. de Agronomía, Universidad de la República de Uruguay

Non-radioactive tracers are very important for agricultural, biological, chemical and medical research and 15N is not the exception. In order to be able to measure 15N abundances, the INGEIS (Geochronology and Isotopic Geology Institute, Buenos Aires, Argentina) is making an effort to put in operation Jasco NA-1 Analyzer that has been out of service for several years. The equipment is an Emission Spectrometric Analyzer made by the Japan Spectroscopic Company and it is designed for the exclusive purpose o determining concentrations of heavy nitrogen. Once the equipment is turned on and all the basic functions of the instrument checked, the atomic %15N measuring started. The inaccuracy of the measures had been corrected by cubic spline interpolation. The spline is a sum of cubic polynomial functions that work in a range of data (known 15N concentrations in our case). We conclude that the atomic abundances of nitrogen isotopes can be measured by emission spectrometry at INGEIS, Buenos Aires. The cubic spline interpolation is an appropriated method for the development of an inaccuracy correction like the one needed for the Jasco NA-1 Analyzer.  At high 15N concentrations the agreement between the measured values and the recommended values for standard materials is satisfactory. The objectives on the immediate future of this technique team is to prepare samples of known 15N concentration using the Dumas Method, and a  new digital output of the data should be connected in order to reduce the inaccuracy of the measure produced by the analogical strip chart output.