[Mr. Lucky]

The problems with the Miller-Urey experiment are widely discussed in the literature. In order for their "experiment" to work, they had to produce an atmosphere to, among other things, contain no oxygen because an experimental atmosphere which resembled the atmosphere of early earth would have been caustic to the organic molecules they hoped to create. See, for instance Deamer, Microbiology & Molecular Biology Reviews, Vol. 61:239 (1997).

[TexasGator]

” they had to produce an atmosphere to, among other things, contain no oxygen “

That’s the theory. Early there was no oxygen in the atmosphere.