Glyoxylic acid synthesis

In my quest for a non-electrochemical glyoxylic acid synthesis, I've found a few that seem simple and pretty OTC. The first is the reduction of oxalic acid with magnesium metal, which if I'm not mistaken forms a magnesium salt which is unwanted. The second is a mixture of nitric acid and ethyl alcohol, which I couldn't find any kind of yield and it was only briefly mentioned in a patent. The third is the oxidation of a glyoxal solution with nitric acid and again I couldn't find any info on reaction time, yields, and whatnot. Has anyone tried any of these methods with reasonable results?


