The result of your conversion between nanogram/microliter and grain/gallon [US] appears here
To convert between Nanogram/microliter and Grain/gallon [US] you have to do the following:
First divide 1.0E-12/1.0E-9 / ((0.45359237/16)*(192/175)/480)/0.0037854118 = 0.05841783
Then multiply the amount of Nanogram/microliter you want to convert to Grain/gallon [US], use the chart below to guide you.
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