Identification—
Prepare a test solution of it in alcohol containing 2 mg per mL. Prepare a Standard solution of
USP Bacampicillin Hydrochloride RS in alcohol containing 2 mg per mL. Apply two 5-µL portions of the test solution 4.0 cm apart to a thin-layer chromatographic plate coated with a 0.25-mm layer of chromatographic silica gel mixture (see
Chromatography 
621
). After the spots dry, apply two 5-µL portions of the Standard solution, one midway between the test solution spots and the other to one of the test solution spots. Allow the spots to dry, place the plate in a suitable chromatographic chamber, and develop the chromatogram in a solvent system consisting of a mixture of methylene chloride, chloroform, and alcohol (10:1:1). When the solvent front has moved about three-fourths of the length of the plate, remove the plate from the chamber, and allow to dry. Spray the plate with a spray reagent containing 1 g of ninhydrin and 1 mL of pyridine in each 100 mL of solution in butyl alcohol, and heat at 100
for 10 minutes: bacampicillin appears as a purple spot, and the
RF values of the spots from the test solution and from the combined test solution and Standard solution, respectively, correspond to the
RF value of the spot obtained from the Standard solution.
Assay—
Mobile phase—
To 500 mL of 0.02 M dibasic sodium phosphate add portions of 0.02 M monobasic sodium phosphate until a pH of 6.8 ± 0.05 is reached. Prepare a suitable filtered mixture of this pH 6.8 buffer and acetonitrile (500:500). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Prepare a solution of
USP Bacampicillin Hydrochloride RS, accurately weighed, in water having a known concentration of about 0.8 mg per mL, sonicating for about 20 minutes to achieve complete dissolution. Pass through a filter of 0.5-µm or finer porosity.
Assay preparation—
Transfer about 80 mg of Bacampicillin Hydrochloride, accurately weighed, to a 100-mL volumetric flask, add 90 mL of water, and sonicate for about 20 minutes. Dilute with water to volume, mix, and pass through a filter of 0.5-µm or finer porosity.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 15-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the
Standard preparation, and record the responses as directed for
Procedure: the column efficiency determined from the analyte peak is not less than 3000 theoretical plates, and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 20 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the area responses for the major peaks. Calculate the quantity, in µg, of ampicillin (C
16H
19N
3O
4S) equivalent in each mg of the Bacampicillin Hydrochloride taken by the formula:
(349.41/501.99)(100,000C / W)(rU / rS),
in which 349.41 and 501.99 are the molecular weights of anhydrous ampicillin and bacampicillin hydrochloride, respectively,
C is the concentration, in mg per mL, of
USP Bacampicillin Hydrochloride RS in the
Standard preparation,
W is the weight, in mg, of the portion of Bacampicillin Hydrochloride taken, and
rU and
rS are the bacampicillin peak area responses obtained from the
Assay preparation and the
Standard preparation, respectively.
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