Tropicamide Ophthalmic Solution »Tropicamide Ophthalmic Solution is a sterile,aqueous solution of Tropicamide.It contains not less than 95.0percent and not more than 105.0percent of the labeled amount of C17H20N2O2.It contains a suitable antimicrobial agent,and may contain suitable substances to increase its viscosity. Packaging and storage— Preserve in tight containers,and avoid freezing. USP Reference standards á11ñ USP Tropicamide RS. Identification— A: Extract 10mLof it with 25mLof chloroform,filter the chloroform extract through dry,folded filter paper,and evaporate the filtrate to dryness:the residue so obtained responds to Identificationtest Aunder Tropicamide. B: The UVabsorption spectrum of the solution employed for measurement of absorbance in the Assayexhibits maxima and minima at the same wavelengths as that of a similar solution of USP Tropicamide RS,concomitantly measured. Sterility á71ñ: meets the requirements. pHá791ñ: between 4.0and 5.8. Assay— Transfer an accurately measured volume of Ophthalmic Solution,equivalent to about 30mg of tropicamide,to a 100-mLvolumetric flask,add water to volume,and mix.Transfer 10.0mLof this solution to a separator,add 2mLof sodium carbonate solution (1in 10),extract with four 20-mLportions of chloroform,and combine the extracts in a second separator.Wash the combined extracts with a 25-mLportion of pH6.5phosphate buffer (see Buffer Solutionsin the section Reagents,Indicators,and Solutions),and transfer to another separator.Wash the aqueous layer with 10mLof chloroform,and add it to the extracts.Extract the chloroform solution with four 20-mLportions of dilute sulfuric acid (1in 6),combine the acid extracts in a 100-mLvolumetric flask,and add the dilute acid to volume.Dissolve an accurately weighed quantity of USP Tropicamide RSin dilute sulfuric acid (1in 6),and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 30µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 253nm,with a suitable spectrophotometer,using dilute sulfuric acid (1in 6)as the blank.Calculate the quantity,in mg,of C17H20N2O2in each mLof the Ophthalmic Solution taken by the formula: (C/V)(AU/AS), in which Cis the concentration,in µg per mL,of USP Tropicamide RSin the Standard solution,Vis the volume,in mL,of Ophthalmic Solution taken,and AUand ASare the absorbances of the solution from the Ophthalmic Solution and the Standard solution,respectively. Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist Expert Committee:(PA6)Pharmaceutical Analysis 6 USP28–NF23Page 1998 Phone Number:1-301-816-8389