» Dichlorphenamide contains not less than 98.0 percent and not more than 101.0 percent of C6H6Cl2N2O4S2, calculated on the dried basis.
Packaging and storage Preserve in well-closed containers.
A: To 10 mL of a 1 in 10,000 solution in sodium hydroxide solution (1 in 2500) add 0.1 mL of hydrochloric acid: it exhibits absorption maxima at 295 ± 2 nm and at 286 ± 2 nm. The ratio A295 / A286 is between 0.90 and 1.00.
Melting range 741: between 236.5 and 240.
Loss on drying 731 Dry it at a pressure not exceeding 5 mm of mercury at 100 to constant weight: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.2%.
Chloride 221 To 100 mg add 25 mL of 8 N nitric acid, and warm on a steam bath to dissolve. Cool to room temperature: the solution shows no more chloride than corresponds to 0.28 mL of 0.020 N hydrochloric acid (0.20%).
Selenium 291: 0.003%, a 100-mg test specimen, mixed with 100 mg of magnesium oxide, being used.
Heavy metals, Method II 231: 0.001%.
Mobile solvent Prepare a suitable solution of 0.02 M monobasic sodium phosphate and 0.02 M dibasic sodium phosphate in acetonitrile and water (approximately 1:1) such that the retention time of Dichlorphenamide is approximately 6 minutes.
Standard preparation Dissolve an accurately weighed quantity of USP Dichlorphenamide RS in Mobile solvent to obtain a solution containing about 1 mg per mL.
Assay preparation Accurately weigh about 50 mg of Dichlorphenamide, and prepare as directed for Standard preparation.
Procedure Introduce separately 20-µL portions of the Assay preparation and the Standard preparation into a high-pressure liquid chromatograph (see Chromatography 621) operated at 25, by means of a suitable microsyringe or sampling valve, adjusting the operating parameters such that the peak obtained with the Standard preparation is full-scale. Typically, the apparatus is fitted with a 4-mm × 30-cm column, packed with packing L1, is equipped with an UV detector capable of monitoring absorption at 280 nm and a suitable recorder, and is capable of operating at a column pressure of up to 3500 psi. Five replicate injections of the Standard preparation show a relative standard deviation of not more than 1.5%. Calculate the quantity, in mg, of C6H6Cl2N2O4S2 in the portion of Dichlorphenamide taken by the formula:
50C(AU / AS)in which C is the concentration, in mg per mL, of USP Dichlorphenamide RS in the Standard preparation; and AU and AS are the area responses obtained at equivalent retention times from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information Please check for your question in the FAQs before contacting USP.Chromatographic Column
USP32NF27 Page 2121Pharmacopeial Forum: Volume No. 29(4) Page 1025
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.