Add the following:

Add the following:

pH4.4Sodium phosphate buffer— Dissolve 7.8g of monobasic sodium phosphate in 900mLof water,adjust with phosphoric acid or 10Nsodium hydroxide to a pHof 4.4±0.1,dilute with water to 1000mL,and mix.

Mobile phase— Prepare a suitable mixture of pH4.4Sodium phosphate bufferand methanol (95:5),and pass through a filter having a 0.5-µm or finer porosity.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve accurately weighed quantities of USP Amoxicillin RSand USP Clavulanate Lithium RSin water to obtain a solution having known concentrations of about 0.5mg per mLand 0.2mg per mL,respectively.

Assay preparation— Dilute an accurately measured volume of Amoxicillin and Clavulanic Acid for Oral Suspension,constituted as directed in the labeling,quantitatively with water to obtain a solution containing about 0.5mg of amoxicillin per mL.Stir by mechanical means for 10minutes,and filter.Use the filtrate as the Assay preparationwithin 1hour of the dilution of the suspension.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 220-nm detector and a 4-mm ×30-cm column that contains 3-to 10-µm packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,between the amoxicillin and clavulanic acid peaks is not less than 3.5;the column efficiency determined from each analyte peak is not less than 550theoretical plates;the tailing factor for each analyte peak is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 0.5for clavulanic acid and 1.0for amoxicillin.Calculate the quantity,in mg,of amoxicillin (C16H19N3O5S)in each mLof the constituted Amoxicillin and Clavulanate Potassium for Oral Suspension taken by the formula: in which Cis the concentration,in mg per mL,of USP Amoxicillin RSin the Standard preparation;Pis the potency,in µg of amoxicillin per mg,of USP Amoxicillin RS;Lis the labeled quantity,in mg per mL,of amoxicillin in the constituted Amoxicillin and Clavulanate Potassium for Oral Suspension;Dis the concentration,in mg per mL,of amoxicillin in the Assay preparationon the basis of the labeled quantity of amoxicillin in the constituted Amoxicillin and Clavulanate Potassium for Oral Suspension,the volume of constituted Oral Suspension taken,and the extent of dilution;and rUand rSare the amoxicillin peak responses obtained from the Assay preparationand the Standard preparation,respectively.Calculate the quantity,in mg,of clavulanic acid (C8H9NO5)in each mLof the constituted Amoxicillin and Clavulanate Potassium for Oral Suspension taken by the formula: in which Lis the labeled quantity,in mg per mL,of clavulanic acid in the constituted Amoxicillin and Clavulanate Potassium for Oral Suspension;Dis the concentration,in mg per mL,of clavulanic acid in the Assay preparationon the basis of the labeled quantity of clavulanic acid in the constituted Oral Suspension,the volume of constituted Oral Suspension taken,and the extent of dilution;Cis the concentration,in mg per mL,of USP Clavulanate Lithium RSin the Standard preparation;Pis the designated potency,in µg of clavulanic acid per mg,of the USP Clavulanate Lithium RS;and rUand rSare the clavulanic acid peak responses obtained from the Assay preparationand the Standard preparation,respectively.