pH 7.3 Dye-buffer solution— Prepare a solution containing, in each 500 mL, 200 mg of bromothymol blue, 3.2 mL of 0.1 N sodium hydroxide, 577.5 mg of citric acid monohydrate, and 6.3 mg of anhydrous dibasic sodium phosphate.

Test solution— Finely powder 1 Tablet, and transfer an amount, equivalent to about 0.5 mg of methscopolamine bromide, to a suitable container. Add 20 mL of water, heat for 5 minutes on a steam bath with frequent agitation, and centrifuge to obtain a clear supernatant. Transfer 10 mL of the supernatant to a vessel containing 10 mL of chloroform and 10 mL of pH 7.3 Dye-buffer solution. Shake vigorously for 3 minutes, centrifuge, and transfer 8 mL of the chloroform layer to a suitable container. Evaporate to dryness, and dissolve the residue in 1 mL of chloroform.

Standard solution— Prepare a solution in water containing about 0.025 mg of USP Methscopolamine Bromide RS per mL, and treat as directed above, beginning with “Transfer 10 mL of the supernatant.”

Application volume: 50 µL.

Developing solvent system— In a suitable container, mix water, butyl alcohol, and glacial acetic acid (5:4:1), then transfer a measured volume of the upper organic layer to a suitable container, and mix with a volume of alcohol equivalent to 20% of the volume of the organic layer.

Procedure— Allow the solvent front to move about three-fourths of the length of the plate, remove the plate from the developing chamber, mark the solvent front, and dry the plate under a current of air for 30 minutes. Spray the plate evenly with potassium–bismuth iodide TS: the chromatogram of the Test solution shows a bright orange spot on a yellow background corresponding in RF value (about 0.25) to that in the chromatogram obtained from the Standard solution. [Note—Bromothymol blue produces a dark yellow spot at an RF value of about 0.8.]

Determine the percentage of the labeled amount of methscopolamine bromide dissolved using the following method.

FOR TABLETS THAT CONTAIN 2.5 MG OF METHSCOPOLAMINE BROMIDE— Place 10 Tablets in a 100-mL volumetric flask, add about 50 mL of Mobile phase, and sonicate for 30 minutes. Shake by mechanical means for 30 minutes, dilute with Mobile phase to volume, and mix. Pass a portion through a 0.45-µm PTFE filter, discarding the first 2 to 3 mL of the filtrate.

FOR TABLETS THAT CONTAIN 5 MG OF METHSCOPOLAMINE BROMIDE— Place 10 Tablets in a 200-mL volumetric flask, add about 100 mL of Mobile phase, and sonicate for 30 minutes. Shake by mechanical means for 30 minutes, dilute with Mobile phase to volume, and mix. Pass a portion through a 0.45-µm PTFE filter, discarding the first 2 to 3 mL of the filtrate.

100C(rU / rS)