by Guest » Fri Sep 22, 2006 6:32 pm
Look up atomic weight of mercury, which is also the number of grams per mole. If you multiply it by nanomoles, you get nanograms.
I don't know how much a liter of blood weighs, it must be close to, but slightly greater than 1 kg.
ng/kg would give parts per trillon as they are 10^12 apart, but your number may be large enough to move decimal and adjust. I think you are talking parts per billion, but I didn't do the math.