Medium: 0.01 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C2H5NO2 dissolved, employing the procedure set forth in the Assay, using a filtered portion of the solution under test as the Assay preparation in comparison with a Standard solution having a known concentration of USP Acetohydroxamic Acid RS in the same Medium.

Tolerances— Not less than 85% (Q) of the labeled amount of C2H5NO2 is dissolved in 30 minutes.

Phosphate buffer, Pyridoxal 5-phosphate solution, and Standard solutions— Prepare as directed in the test for Limit of hydroxylamine under Acetohydroxamic Acid.

Test solution— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 1500 mg of acetohydroxamic acid to a 50-mL stoppered centrifuge tube. Add 30.0 mL of water, shake for about 2 minutes, and centrifuge. Pipet 15.0 mL of the clear solution into a 50-mL beaker, add just enough water to cover the electrode of a calibrated pH meter, and while stirring, adjust with 0.5 M potassium hydroxide to a pH of 7.4. Quantitatively transfer the contents of the beaker, with the aid of small portions of water, to a 50-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Proceed as directed in the test for Limit of hydroxylamine under Acetohydroxamic Acid, except to calculate the percentage of hydroxylamine (H3NO) in the portion of Tablets taken by the formula: in which A is the average weight, in mg, of each Tablet; S is the weight, in mg, of the portion of Tablets taken to prepare the Test solution; L is the labeled amount, in mg, of acetohydroxamic acid per Tablet; and the other terms are as defined therein. Not more than 0.5% is found.

(Official January 1, 2007)

Ferric chloride solution and Standard preparation— Prepare as directed in the Assay under Acetohydroxamic Acid.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 500 mg of acetohydroxamic acid, to a 1000-mL volumetric flask, add about 500 mL of 0.1 N hydrochloric acid, and shake for 1 minute. Dilute with 0.1 N hydrochloric acid to volume, and mix. Filter, discarding the first 40 mL of the filtrate. Use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay under Acetohydroxamic Acid. Calculate the quantity, in mg, of C2H5NO2 in the portion of Tablets taken by the formula: