A: Thin-Layer Chromatographic Identification Test 201—

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Add the following:

Medium: pH 7.5 phosphate buffer (prepared by dissolving 6.81 g of potassium dihydrogen phosphate in 800 mL of water, adjusting the pH to 7.5 with 0.5 N sodium hydroxide, and diluting with water to 1 L); 900 mL.

Apparatus 2: 75 rpm.

Time: 30 minutes.

Standard solution—

Test solution— Use portions of the solution under test passed through a suitable 10-µm filter, discarding the first few mL.

Procedure— Determine the percentage of the labeled amount of meloxicam dissolved by employing UV absorption, using a suitable spectrophotometer, at the wavelength of maximum absorbance at about 362 nm, using 1-cm cuvettes, on the Test solution in comparison with the Standard solution using Medium as blank. Calculate the percentage of meloxicam dissolved by the formula: in which AU and AS are the absorbances obtained from the Test solution and the Standard solution, respectively; CS is the concentration, in mg per mL, of the Standard solution; 900 is the volume, in mL, of Medium; 100 is the conversion factor to percentage; and LC is the Tablet label claim, in mg.

Tolerances— Not less than 70% (Q) of the labeled amount of meloxicam is dissolved in 30 minutes.3

Solution A, Solution B, and Mobile phase— Proceed as directed in the Assay.

Standard solution— Use the Standard preparation from the Assay.

System sensitivity solution— Transfer 4 mL of the Standard solution to a 100-mL volumetric flask, dilute with methanol to volume, and mix. Transfer 5 mL of the resulting solution to a 50-mL volumetric flask, add 5 mL of 1 N sodium hydroxide, and dilute with methanol to volume.

Test solution— Use the Assay preparation.

Chromatographic system (see Chromatography 621)— Proceed as directed in the Assay, except to chromatograph the Standard solution and the System sensitivity solution: the tailing factor for the meloxicam peak is not more than 2.0; the relative standard deviation for replicate injections of the Standard solution is not more than 2.0%; and the signal-to-noise ratio of the meloxicam peak in the chromatogram of the System sensitivity solution is not less than 10.

Procedure— Separately inject equal volumes (about 25 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Determine the relative retention times for the impurity peaks relative to that of the meloxicam peak. Calculate the percentage of each impurity in the portion of Tablets taken by the formula: in which F is the relative response factor for each impurity and is equal to 2.7 for the impurity with a relative retention time of about 0.5 (meloxicam related compound B [2-amino-5-methylthiazole]) and 1.0 for all other impurities; C is the concentration, in mg per mL, of USP Meloxicam RS in the Standard solution; W is the weight, in mg, of powdered Tablets taken to prepare the Test solution; A is the average weight of a Tablet; L is the labeled amount, in mg, of meloxicam in each Tablet; ri is the peak response obtained for each impurity in the Test solution; and rS is the peak response for meloxicam in the Standard solution: not more than 0.15% of meloxicam related compound B is found; not more than 0.2% of any individual unknown impurity is found; and not more than 0.5% of total impurities is found.

Solution A— Dissolve 2.0 g of dibasic ammonium phosphate in 1 L of water, and adjust with phosphoric acid to a pH of 7.0 ± 0.1.

Solution B— Mix 650 mL of methanol and 100 mL of isopropyl alcohol.

Mobile phase— Prepare a filtered and degassed mixture of Solution A and Solution B (63:37). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard stock preparation— [note—The Standard stock preparation is prepared so that the final concentration of meloxicam, in mg per mL, is approximately equivalent to the concentration of the Assay stock preparation.] Transfer a suitable quantity of USP Meloxicam RS, accurately weighed, to a 50-mL volumetric flask, dissolve in 1 mL of 1 N sodium hydroxide and 30 mL of methanol, and dilute with methanol to volume. Transfer 10 mL of the resulting solution to a 100-mL volumetric flask, add 10 mL of 1 N sodium hydroxide, and dilute with methanol to volume.

Standard preparation— Transfer 15 mL of the Standard stock preparation to a 25-mL volumetric flask, and dilute with water to volume.

Assay stock preparation— Transfer 10 Tablets to a 1000-mL volumetric flask, add about 100 mL of 1 N sodium hydroxide, shake to disperse the Tablets, and add 800 mL of methanol. Sonicate the solution for about 15 minutes, then stir for 30 minutes. Dilute with methanol to volume, and mix. Filter the resulting solution, and use the filtrate.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector, a guard column that contains packing L1, and a 4-mm ×10-cm column that contains packing L1. The flow rate is about 0.8 mL per minute. The column temperature is maintained at 40. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor for the meloxicam peak is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 25 µL) of the Standard preparation and the Assay preparation to the chromatograph, record the chromatograms, and measure the responses for the meloxicam peak. Calculate the quantity, in mg, of meloxicam (C14H13N3O4S2) in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Meloxicam RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.