Bruce and all,

Several months ago, we bought a tank of scientific grade CO from Air
Liquide, and discovered that the 29/28 was ca 0.007 and 30/28 was ca. 0.002,
identical to what you describe.  I dont know what production method would
cause such depleted values.  We just bought another tank from MG, and are
crossing our fingers that the 29/28 and 30/28 mass ratios are more
reasonable.

Cheers, Geoff

        [snip]
> We have a tank of CO that's showing 29/28 ratios of around 0.007 and 30/28
> ratios of around 0.002.  The supplier, Air Liquide, says they make the CO
> from natural gas, but that 29/28 ratio would put the delta 13C at around
> -380 per mil PDB, which doesn't seem reasonable.  I figure we've either
> been sold a tank of N2 pretending to be CO, or that there's something
> involved in the production of CO that makes it really light that I don't
> know about.  Has anyone else seen a tank of CO like this?  Any other
> insights?
>
> Thanks,
>
> Bruce Hungate
        [snip]