Oil- and Water-Soluble Vitamins with Minerals Oral Solution Oil- and ...

Assay for niacin or niacinamide— [note—Use low-actinic glassware throughout this procedure.]
Diluting solution— Dissolve 25 g of edetate disodium in 1000 mL of water, and mix.
Mobile phase— Mix 0.4 mL of triethylamine, 15.0 mL of glacial acetic acid, and 350 mL of
methanol, and dilute with 0.008 M sodium 1-hexanesulfonate to 2000 mL. Filter, and degas. Make
adjustments if necessary.
Standard preparation— [note—Use USP Niacin RS for Oral Solution that contains niacin and
USP Niacinamide RS for Oral Solution that contains niacinamide.] Dissolve an accurately
weighed quantity of USP Niacin RS or USP Niacinamide RS in Diluting solution in a volumetric
flask, and dilute quantitatively, and stepwise if necessary, with Diluting solution to obtain a
solution having a known concentration of about 0.10 mg per mL.
Assay preparation— Transfer an accurately measured volume of Oral Solution to a volumetric
flask, dissolve in Diluting solution, and dilute quantitatively, and stepwise if necessary, with
Diluting solution to obtain a solution having a known concentration of about 0.1 mg of niacin or
niacinamide per mL.
Chromatographic system— The liquid chromatograph is equipped with a 270-nm detector and a
4.6-mm × 25-cm column that contains packing L7. The flow rate is about 2.0 mL per minute.
Chromatograph the Standard preparation, and record the peak areas as directed for Procedure: the
relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 5 µL) of the Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the peak areas.
Calculate the quantity, in mg, of niacin (C 6 H 5 NO 2 ) or niacinamide (C 6 H 6 N 2 O) in each mL of the
Oral Solution taken by the formula:
C(L/D)(r U / r S )
in which C is the concentration, in mg per mL, of USP Niacin RS or USP Niacinamide RS in the
Standard preparation; L is the labeled amount, in mg per mL, of niacin or niacinamide in the Oral
Solution taken; D is the concentration, in mg per mL, of niacin or niacinamide in the Assay
preparation, based on the labeled quantity and the extent of dilution; and rU and rS are the peak
areas for niacin or niacinamide obtained from the Assay preparation and the Standard preparation,
respectively.
Assay for pyridoxine hydrochloride—