Page "Miller–Urey experiment" Paragraph 26

Originally it was thought that the primitive secondary atmosphere contained mostly ammonia and methane.

However, it is likely that most of the atmospheric carbon was CO < sub > 2 </ sub > with perhaps some CO and the nitrogen mostly N < sub > 2 </ sub >.

In practice gas mixtures containing CO, CO < sub > 2 </ sub >, N < sub > 2 </ sub >, etc.

give much the same products as those containing CH < sub > 4 </ sub > and NH < sub > 3 </ sub > so long as there is no O < sub > 2 </ sub >.

The hydrogen atoms come mostly from water vapor.

In fact, in order to generate aromatic amino acids under primitive earth conditions it is necessary to use less hydrogen-rich gaseous mixtures.

Most of the natural amino acids, hydroxyacids, purines, pyrimidines, and sugars have been made in variants of the Miller experiment.