Assay—
Assay preparation 1
(where it is represented as being in a single-dose container)—Constitute Penicillin G Procaine for Injectable Suspension as directed in the labeling. Withdraw all of the withdrawable contents, using a suitable hypodermic needle and syringe, and dilute quantitatively with Buffer No. 1 to obtain a solution containing about 2000 Penicillin G Units per mL. Pipet 2 mL of this solution into each of two glass-stoppered, 125-mL conical flasks.
Assay preparation 2
(where the label states the quantity of penicillin G procaine in a given volume of constituted suspension)—Constitute Penicillin G Procaine for Injectable Suspension as directed in the labeling. Dilute an accurately measured volume of the constituted injectable suspension quantitatively with Buffer No. 1 to obtain a solution containing about 2000 Penicillin G Units per mL. Pipet 2 mL of this solution into each of two glass-stoppered, 125-mL conical flasks.
Procedure—
Proceed as directed for
Procedure under
Iodometric Assay—Antibiotics 
425
. Calculate the quantity, in Penicillin G Units, in the container, or in the portion of constituted injectable suspension taken by the formula:
(
L / 2
D)(
F)(
B 
I),
in which
L is the labeled quantity, in Penicillin G Units, in the container, or in the volume of constituted injectable suspension taken, and
D is the concentration, in Penicillin G Units per mL, of
Assay preparation 1 or of
Assay preparation 2 on the basis of the labeled quantity in the container or in the portion of constituted injectable suspension taken, respectively, and the extent of dilution.
