A: Infrared Absorption á197Kñ.

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

Citrate buffer— Prepare a degassed solution containing 5.82mg of anhydrous dibasic sodium phosphate and 16.7mg of citric acid monohydrate in water.Adjust to a pHof 3.0.

Medium: Citrate buffer;900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Determine the amount of C38H50N6O5dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 240nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,in comparision with a Standard solution having a known concentration of USP Saquinavir Mesylate RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C38H50N6O5is dissolved in 45minutes.

Triethylamine phosphate solution,Mobile phase,System suitability solution,and Chromatographic system— Proceed as directed in the Assayunder Saquinavir Mesylate.

Standard solution— Use the Standard preparation,prepared as directed in the Assayunder Saquinavir Mesylate.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 20µL)of the Test solutionand the Standard solutioninto the chromatograph,record the chromatograms,and measure the peak responses.Calculate the percentage of each impurity in the portion of Capsules taken by the formula: in which Fis a response factor,and is equal to 2for a peak,if present,at a retention time of 0.32relative to saquinavir,to 0.5for peaks,if present,at relative retention times of about 0.38and 0.53,and to 1for all other peaks;670.86and 766.96are the molecular weights of saquinavir and saquinavir mesylate,respectively;Cis the concentration,in mg per mL,of USP Saquinavir Mesylate RSin the Standard solution;Wis the weight,in mg,of Capsule contents taken for the Test solution;riis the peak response for each impurity obtained from the Test solution;and rSis the peak response for saquinavir obtained from the Standard solution:not more than 0.2%of any individual impurity is found,and not more than 1.0%of total impurities is found.

Triethylamine phosphate solution,Mobile phase,System suitability solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Saquinavir Mesylate.

Assay preparation— Empty and combine the contents of not fewer than 10Capsules.Transfer an amount of Capsule contents,equivalent to about 22mg of Saquinavir,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.

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.Calculate the quantity,in mg,of saquinavir (C38H50N6O5)in the portion of Capsules taken by the formula: in which 670.86and 766.96are the molecular weights of saquinavir and saquinavir mesylate,respectively;Cis the concentration,in mg per mL,of USP Saquinavir Mesylate RSin the Standard preparation;and rUand rSare the peaks obtained from theAssay preparationand the Standard preparation,respectively.