The nitrogen containing organic compound, when heated with $CuO$ in a atmosphere of $CO _2$, yields free $N _2$ in addition to $CO _2$ and $H _2 O$.

$C _{ x } H _{ y } N _{ z }+\left(2 x +\frac{ y }{2}\right) CuO \rightarrow x CO _2+\frac{ y }{2} H _2 O +\frac{ z }{2} N _2+\left(2 x +\frac{ y }{2}\right) Cu$

Traces of nitrogen oxides formed, if any, are reduced to nitrogen by passing the gaseous mixture over heated copper gauze.