Diastereoisomer ratio
0.2 M Monobasic ammonium phosphate, Mobile phase, Internal standard solution, Resolution solution, Standard preparation, Assay preparation, and Chromatographic system
Prepare as directed in the Assay.
Procedure
Proceed as directed for Procedure in the Assay. Calculate the ratio of cefuroxime axetil diastereoisomer A to the sum of the cefuroxime axetil diastereoisomers A and B taken by the formula:
r /(rA + rB),
in which
rA and
rB are the peak responses of the cefuroxime axetil diastereoisomers A and B, respectively: between 0.48 and 0.55 is obtained.
Assay
0.2 M Monobasic ammonium phosphate
Dissolve 23.0 g of monobasic ammonium phosphate in water to obtain 1000 mL of solution.
Mobile phase
Prepare a suitable filtered and degassed mixture of
0.2 M Monobasic ammonium phosphate and methanol (620: 380). Make adjustments if necessary (see System Suitability under
Chromatography 621).
Internal standard solution
Prepare a solution of acetanilide in methanol containing 5.4 mg per mL.
Resolution solution
In a 50-mL volumetric flask, mix 10.0 mL of a solution of
USP Cefuroxime Axetil RS in methanol containing 1.2 mg per mL, 5.0 mL of Internal standard solution, and 3.8 mL of a solution of
USP Cefuroxime Axetil Delta-3 Isomers RS in methanol containing 0.16 mg per mL. Dilute with
0.2 M Monobasic ammonium phosphate to volume, and mix.
Standard preparation
Transfer about 30 mg of
USP Cefuroxime Axetil RS, accurately weighed, to a 25-mL volumetric flask, dissolve in methanol, dilute with methanol to volume, and mix. Promptly transfer 10.0 mL of this solution to a 50-mL volumetric flask, add 5.0 mL of
Internal standard solution and 3.8 mL of methanol, dilute with
0.2 M Monobasic ammonium phosphate to volume, and mix.
[NOTEUse this
Standard preparation promptly, or refrigerate and use on the day prepared.
]
Assay preparation
Transfer about 30 mg of Cefuroxime Axetil to a 25-mL volumetric flask, dissolve in methanol, dilute with methanol to volume, and mix. Promptly transfer 10.0 mL of this solution to a 50-mL volumetric flask, add 5.0 mL of Internal standard solution and 3.8 mL of methanol, dilute with 0.2 M Monobasic ammonium phosphate to volume, and mix. [NOTEUse this Assay preparation promptly, or refrigerate and use on the day prepared.]
Chromatographic system (see Chromatography 621)
The liquid chromatograph is equipped with a 278-nm detector and a 4.6- mm × 25-cm column containing 5-µm packing L13. The flow rate is about 1.5 mL per minute. Chromatograph the
Resolution solution, and record the peak responses as directed for
Procedure: the relative retention times are about 0.4 for acetanilide, 0.8 for cefuroxime axetil diastereoisomer B, 0.9 for cefuroxime axetil diastereoisomer A, and 1.0 for cefuroxime axetil delta-3 isomers; the resolution,
R, between cefuroxime axetil diastereoisomer A and B is not less than 1.5; and the resolution,
R, between cefuroxime axetil diastereoisomer A and cefuroxime axetil delta-3 isomers is not less than 1.5. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the column efficiency is not less than 3000 theoretical plates when measured using the cefuroxime axetil diastereoisomer A peak; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in µg, of cefuroxime (C
16H
16N
4O
8S) in each mg of Cefuroxime Axetil taken by the formula:
(WS /WU)(PS /100)(100 K)(RU / RS),
in which
WS is the weight, in mg, of
USP Cefuroxime Axetil RS taken to prepare the
Standard preparation; WU is the weight, in mg, of Cefuroxime Axetil taken to prepare the
Assay preparation; PS is the designated cefuroxime (C
16H
16N
4O
8S) content, in µg per mg, of anhydrous
USP Cefuroxime Axetil RS;
K is the percentage water content of
USP Cefuroxime Axetil RS; and
RU and
RS are the ratios of the sum of the peak responses of the cefuroxime axetil diastereoisomers A and B to the peak response of the internal standard obtained from the
Assay preparation and the
Standard preparation, respectively.