Yep. Erythiol has a molecular weight of 122 g/mol, so 6 mM is the same as 0.732 g/liter.

It should be noted that the cells were exposed to the full concentration in the drinks, so the concentration they encountered is much higher than it is when it has been diluted by all the water in our bodies after we drink it.

Ah. I remember that from desperately trying to wrap my head around it in Chemistry class. Thank you, it's impossible to search for.