ACCURATE DETERMINATION OF NITROGEN CONCENTRATIONS BY STATIC VACUUM MASS-SPECTROMETRY

Herein is described a mass spectrometer and associated extraction line for accurate determination of the abundance of nitrogen in a variety of samples including meteorites, lunar samples, diamonds, organic comp ounds and ammonium-bearing rocks and minerals. The error is of the ord er of +/-5% or less for samples containing between 22 wt% N and a few parts per million of N. Perhaps the most important control on the accu racy of the results is the reliability of the N content of the materia ls used for standardization. Whilst commercially available standards c an be used for samples containing N at the percentage level, for sampl es containing trace amounts of N, reference materials need to be synth esized in the laboratory prior to analysis. We strongly urge that a ne w international reference material be synthesized for use during deter mination of trace abundances of N.