A: Thin-Layer Chromatographic Identification Test 201
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.
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.
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.
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.
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 potassiumbismuth 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. [NoteBromothymol blue produces a dark yellow spot at an RF value of about 0.8.]
Powder a number of Tablets, equivalent to about 5 mg of methscopolamine bromide, digest with 5 mL of water for 10 minutes, and filter: a portion of the clear solution so obtained responds to the test for Bromide 191.