Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C7H6KNO2 dissolved by employing UV absorption at the wavelength of maximum absorbance at about 270 nm on filtered portions of the solution under test, suitably diluted with Medium, in comparison with a Standard solution having a known concentration of USP Aminobenzoate Potassium RS in the same Medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C7H6KNO2 is dissolved in 45 minutes.

Standard preparation— Prepare a solution of USP Aminobenzoate Potassium RS having a known concentration of about 5 µg per mL.

Assay preparation— Remove as completely as possible, and combine, the contents of not fewer than 20 Capsules. Transfer an accurately weighed portion of the combined contents, equivalent to about 100 mg of aminobenzoate potassium, to a 200-mL volumetric flask, add 150 mL of water, shake by mechanical means for 30 minutes, dilute with water to volume, mix, and filter. Pipet 2 mL of the filtrate into a 200-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Concomitantly determine the absorbances of the Standard preparation and the Assay preparation at the wavelength of maximum absorbance at about 270 nm, with a suitable spectrophotometer, using water as the blank. Calculate the quantity, in mg, of aminobenzoate potassium (C7H6KNO2) in the portion of Capsule contents taken by the formula: in which C is the concentration, in µg per mL, of USP Aminobenzoate Potassium RS in the Standard preparation; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.