200-400 for what?
gram, mol, oz?
Or are you talking about some altcoin?
If we are talking about standard oz then :
28.35 grams of gold / oz
.144 moles/liter ....
If we are talking about Troy oz then :
31.1 grams of gold / Toz
.158 moles/liter
...
Addition Hope that helped clear up your confusion about the topic!
added those calculations just for the hell of it =]
=]