IMPROVED TECHNIQUES FOR THE EXTRACTION, PURIFICATION AND QUANTIFICATION OF NANOMOLE QUANTITIES OF NITROGEN GAS - THE NITROGEN-CONTENT OF DIAMOND

Herein are described an analytical system and techniques for the purif ication and quantification of nanomole quantities of nitrogen gas. Pre vious designs have been reevaluated and simplified where possible. The use of a capacitance manometer for quantification has been assessed a nd results from reference materials suggest that, for samples of nitro gen greater than 12.5 nmol N-2, the error in the abundance measurement is of the order of +/- 2.5%. The advantages of using a capacitance ma nometer are that, compared with a mass spectrometer, the instrument is easier to calibrate and the calibration factor remains stable for pro tracted periods(>1 year). The procedure for purification has been re-e valuated and simplified and, in particular, is now less reliant on liq uid nitrogen, which may aid in the automation of such analytical syste ms. The nitrogen content of type IaA diamonds, in relation to the infr ared absorption coefficient measured at a wavenumber of 1282 cm(-1) (m u(1282) cm(-1)), has been investigated. The results obtained with the new system (k(A) = 16.1 +/- 1 ppm(at) cm) are similar to those of Wood s et al, who used an inert gas fusion technique.