The result of your conversion between microgram/liter and grain/quart [US] appears here
To convert between Microgram/liter and Grain/quart [US] you have to do the following:
First divide 1.0E-9/0.001 / ((0.45359237/16)*(192/175)/480)/(0.0037854118/4) = 0.0000146
Then multiply the amount of Microgram/liter you want to convert to Grain/quart [US], use the chart below to guide you.
Symbol: µg/l
No description
Symbol: gr/qt
No description