| A new procedure for the conversion of bound nitrogen into nitrogen gas, applicable to solid material, is described. It embodies two main stages: the catalytic ammonification of the sample and the consecutive transformation of ammonium to molecular nitrogen by the modified Dumas method. The first step of the preparation is carried out in a quartz reactor, filled with granular nickel, at a temperature of 700°C, the ammonia gas produced being trapped in sulphuric acid. In the second step, this solution is neutralised, dried and subjected to the Dumas combustion.The addition of reagents does not influence the results of the measurements. Spectrometric <sup>15</sup>N percentage abundances are converted into mass spectrometric "true"... |
