A: Triturate a quantity of finely powdered Tablets, equivalent to about 100 mg of dyphylline, with 20 mL of water, and transfer to a test tube. Add 2.0 mL of 2 N sodium hydroxide and 2 drops of potassium permanganate TS: a green color is produced.

B: Triturate a quantity of finely powdered Tablets, equivalent to about 100 mg of guaifenesin, with 10 mL of chloroform, filter, and on a watch glass evaporate 1 mL of the filtrate, on a steam bath, to dryness. To the residue add 1 drop of formaldehyde TS and a few drops of sulfuric acid: a deep cherry-red to purple color is produced.

C: The retention times of the major peaks in the chromatogram of the Assay preparation correspond to those in the chromatogram of the Standard preparation, as obtained in the Assay.

Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amounts of dyphylline (C10H14N4O4) and guaifenesin (C10H14O4) dissolved, using the procedure set forth in the Assay, making any necessary modifications.

Tolerances— Not less than 75% (Q) of the labeled amounts of C10H14N4O4 and C10H14O4 are dissolved in 45 minutes.

(Official January 1, 2007)

Mobile phase, Resolution solution, and Standard preparation— Prepare as directed in the Assay under Dyphylline and Guaifenesin Elixir.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of guaifenesin, to a 100-mL volumetric flask, add about 80 mL of Mobile phase, sonicate for 30 minutes, and shake by mechanical means for an additional 30 minutes. Dilute with Mobile phase to volume, mix, and pass through a membrane filter having a 0.45-µm or finer porosity, discarding the first 10 mL of the filtrate. Transfer 5.0 mL of the clear filtrate to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Chromatographic system— Prepare as directed in the Assay under Dyphylline and Guaifenesin Elixir, except omit the use of the guard column.

Procedure— Proceed as directed in the Assay under Dyphylline and Guaifenesin Elixir. Calculate the quantities, in mg, of dyphylline (C10H14N4O4) and guaifenesin (C10H14O4) in the portion of Tablets taken by the formula: in which the terms are as defined therein.