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C8H10N2S 166.24

4-Pyridinecarbothioamide, 2-ethyl-.
2-Ethylthioisonicotinamide [536-33-4].
» Ethionamide contains not less than 98.0 percent and not more than 102.0 percent of C8H10N2S, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight containers.
B: Ultraviolet Absorption 197U—Test solution versus standard solution, prepared as directed in the Assay.
Melting range: 741: between 158 and 164.
pH 791: between 6.0 and 7.0, in a 1 in 100 slurry in water.
Water, Method I 921: not more than 2.0%.
Residue on ignition 281: not more than 0.2%.
Selenium 291: 0.003%, a 200-mg test specimen being used.
Assay— Transfer about 100 mg of Ethionamide, accurately weighed, to a 250-mL volumetric flask, dissolve in about 100 mL of methanol, dilute with methanol to volume, and mix. Transfer a 5-mL aliquot to a 200-mL volumetric flask, dilute with methanol to volume, and mix (test solution). Dissolve a suitable quantity of USP Ethionamide RS, accurately weighed, in methanol, and dilute quantitatively and stepwise with methanol to obtain a Standard solution having a known concentration of about 10 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 290 nm, with a suitable spectrophotometer, using methanol as the blank. Calculate the quantity, in mg, of C8H10N2S in the portion of Ethionamide taken by the formula:
10C(AU / AS)
in which C is the concentration, in µg per mL, of USP Ethionamide RS in the Standard solution, and AU and AS are the absorbances of the test solution and the Standard solution, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
(MDAA05) Monograph Development-Antivirals and Antimicrobials
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 2324
Pharmacopeial Forum: Volume No. 33(4) Page 648
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.