B-12 Injection

I need help on billing B12 injections. We administer 1 ml to each patient. But, insurance payers reimburse by unit. Like BCBS they pay .60 per unit. So, 1ml is 1000 units. J3420 is up to 1000 mcg's. If we give 1 ml, how many mcg's would that equal to? I would hate to bill 1000 units @ .60 each unit $600.00. Will you please explain to me how to bill B12 injections? Thank you.