A: Infrared Absorption 197K.

B: The retention time of the acarbose peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Test solution: 10 mg per mL, in water.

Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay.

Test solution— Use the Assay preparation.

Diluted test solution— Transfer 1.0 mL of the Test solution to a 100-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Separately inject equal volumes (about 10 µL) of the Test solution and the Diluted test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity in the portion of Acarbose taken by the formula: in which F is the relative response factor for each impurity, as listed in Table 1; ri is the individual peak response for each impurity; and rA is the response of the main acarbose peak in the chromatogram obtained from the Diluted test solution. In addition to not exceeding the limits for each impurity in Table 1, not more than 3.0% of total impurities is found.

Phosphate buffer— Dissolve 0.6 g of monobasic potassium phosphate and 0.35 g of dibasic sodium phosphate in 900 mL of water, dilute with water to 1 L, and mix.

Mobile phase— Prepare a mixture of acetonitrile and Phosphate buffer (750:250). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Reconstitute a vial of USP Acarbose RS in 5.0 mL of water.

System suitability solution— Reconstitute a vial of USP Acarbose System Suitability Mixture RS in 1 mL of water.

Assay preparation— Transfer about 200 mg of Acarbose, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with water to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 210-nm detector and a 4-mm × 25-cm column that contains packing L8. The flow rate is about 2 mL per minute. The column temperature is maintained at 35. Chromatograph the System suitability solution, and identify the acarbose peak and the peaks due to the impurities listed in Table 1. Record the peak responses as directed for Procedure: the ratio of the height of the impurity A peak to the height of the valley between the impurity A peak and the acarbose peak is not less than 1.2. The chromatogram obtained is similar to the chromatogram supplied with USP Acarbose System Suitability Mixture RS.

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 all the peaks. Calculate the quantity, in mg, of C25H43NO18 in the portion of Acarbose taken by the formula: in which C is the concentration, in mg per mL, of USP Acarbose RS in the Standard preparation; and rU and rS are the acarbose peak responses obtained from the Assay preparation and the Standard preparation, respectively.1S (USP31)