Adsorbent: chromatographic silica gel.

Developing solvent: mixture of chloroform and diethylamine (9:1).

Test preparation— Use undiluted. Apply 15 µL.

Detection reagent: potassium iodoplatinate TS.

Procedure— Proceed as directed for Procedure under Thin-Layer Chromatographic Identification Test 201, the spots on the plate located by spraying with Detection reagent.

(Official January 1, 2007)

Acetate buffer— Prepare a solution in water containing in each L 0.05 mole of sodium acetate and 2.9 mL of glacial acetic acid.

Mobile phase— Transfer 5.1 g of tetrabutylammonium hydrogen sulfate to a 1-L volumetric flask, add 50 mL of acetonitrile, and dilute with Acetate buffer to volume. Adjust with 5 N sodium hydroxide to a pH of 5.5 ± 0.1.

Standard preparation— Dissolve an accurately weighed quantity of USP Atropine Sulfate RS in water, and dilute quantitatively with water to obtain a solution having a known concentration of about 80 µg per mL.

Assay preparation— Transfer an accurately measured volume of Injection, equivalent to about 2 mg of atropine sulfate, to a 25-mL volumetric flask, dilute with water to volume, and mix.

Resolution solution— Prepare a solution in water containing about 2.5 µg of p-hydroxybenzoic acid per mL. Dilute one volume of this solution with four volumes of the Standard preparation.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and 30-cm × 3.9-mm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 1.5%. In a similar manner, chromatograph the Resolution solution: the retention time of p-hydroxybenzoic acid is about 1.6 relative to that of atropine, and the resolution, R, between the p-hydroxybenzoic acid and atropine peaks is not less than 2.2.

Procedure— Separately inject equal volumes (about 100 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in mg, of (C17H23NO3)2·H2SO4·H2O in each mL of the Injection taken by the formula: in which 694.85 and 676.83 are the molecular weights of atropine sulfate monohydrate and anhydrous atropine sulfate, respectively; C is the concentration, in mg per mL, of USP Atropine Sulfate RS in the Standard preparation; V is the volume, in mL, of Injection taken; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.