Sulfachlorpyridazine
(sul'' fa klor'' pir id' a zeen).
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284.72N1-(6-Chloro-3-pyridazinyl)sulfanilamide
[80-32-0].» Sulfachlorpyridazine contains not less than 97.0 percent and not more than 103.0 percent of C10H9ClN4O2S, calculated on the dried basis.
Packaging and storage—
Preserve in well-closed, light-resistant containers.
Labeling—
Label it to indicate that it is for veterinary use only.
USP Reference standards 
11
—
11—
USP Sulfachlorpyridazine RS 
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Identification—
Clarity and color of solution—
Dissolve 1.0 g of it in 50 mL of 0.1 N methanolic hydrochloric acid prepared by diluting 8.6 mL of hydrochloric acid with methanol to obtain 1000 mL of solvent: a clear solution is produced that is not deeper in color than pale yellow.
Acidity—
Prepare a suspension of 3.0 g of it in 150.0 mL of carbon dioxide-free water, and heat at 70
for 5 minutes, maintaining the suspension. Cool rapidly in an ice bath to 20 ± 0.5, stirring by mechanical means. Filter the suspension using vacuum, and collect the filtrate. Titrate 25.0 mL of the clear filtrate with 0.1 N sodium hydroxide VS, using 2 drops of thymolphthalein TS as the indicator. Transfer a second 25.0-mL portion of the clear filtrate to a 250-mL conical flask, add 10 mL of hydrochloric acid, and cool in an ice bath to 15. Add about 25 g of crushed ice, prepared from frozen purified water, and titrate with 0.1 M sodium nitrite VS, stirring vigorously, until the titrated solution produces an immediate, stable, blue color on starch-iodide paper. The volume of 0.1 N sodium hydroxide consumed in the titration of the first 25.0-mL portion of the filtrate does not exceed the volume of 0.1 M sodium nitrite consumed in the titration of the second 25.0-mL portion of the filtrate by more than 0.5 mL.
for 5 minutes, maintaining the suspension. Cool rapidly in an ice bath to 20 ± 0.5, stirring by mechanical means. Filter the suspension using vacuum, and collect the filtrate. Titrate 25.0 mL of the clear filtrate with 0.1 N sodium hydroxide VS, using 2 drops of thymolphthalein TS as the indicator. Transfer a second 25.0-mL portion of the clear filtrate to a 250-mL conical flask, add 10 mL of hydrochloric acid, and cool in an ice bath to 15. Add about 25 g of crushed ice, prepared from frozen purified water, and titrate with 0.1 M sodium nitrite VS, stirring vigorously, until the titrated solution produces an immediate, stable, blue color on starch-iodide paper. The volume of 0.1 N sodium hydroxide consumed in the titration of the first 25.0-mL portion of the filtrate does not exceed the volume of 0.1 M sodium nitrite consumed in the titration of the second 25.0-mL portion of the filtrate by more than 0.5 mL.
Loss on drying 731:
Dry it at 105 for 3 hours: it loses not more than 0.5% of its weight.
731:
Dry it at 105 for 3 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281:
not more than 0.1%.
281:
not more than 0.1%.
Heavy metals, Method II 231:
0.002%.
231:
0.002%.
Assay—
pH 2.5 phosphate buffer—
Dissolve 14 g of monobasic potassium phosphate in 1600 mL of water, adjust with phosphoric acid to a pH of 2.5 ± 0.1, dilute with water to 2000 mL, and mix.
Mobile phase—
Prepare a filtered and degassed mixture of pH 2.5 phosphate buffer and methanol (700:300). Make adjustments if necessary (see System Suitability under Chromatography 621).
621).
Standard preparation—
Prepare a stock solution of USP Sulfachlorpyridazine RS in methanol having a known concentration of about 0.5 mg per mL. Transfer 3.0 mL of this stock solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix. Filter this solution through a nylon filter having a porosity of 0.5 µm or finer, and use the filtrate as the Standard preparation. The Standard preparation contains about 15 µg of USP Sulfachlorpyridazine RS per mL.
Assay preparation—
Transfer about 50 mg of Sulfachlorpyridazine, accurately weighed, to a 100-mL volumetric flask. Dissolve in and dilute with methanol to volume, and mix. Transfer 3.0 mL of this solution to a second 100-mL volumetric flask, dilute with Mobile phase to volume, and mix. Filter this solution through a filter having a porosity of 0.5 µm or finer, and use the filtrate as the Assay preparation.
Chromatographic system
(see Chromatography 621)—The liquid chromatograph is equipped with a 265-nm detector, a 4.6-mm × 25-cm analytical column containing 5-µm packing L1, and a guard column containing 5-µm packing L1, and is maintained at about 40. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.
621)—The liquid chromatograph is equipped with a 265-nm detector, a 4.6-mm × 25-cm analytical column containing 5-µm packing L1, and a guard column containing 5-µm packing L1, and is maintained at about 40. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C10H9ClN4O2S in the portion of Sulfachlorpyridazine taken by the formula:
(10 / 3)(C)(rU / rS)
in which C is the concentration, in µg per mL, of USP Sulfachlorpyridazine RS in the Standard preparation; and rU and rS are the sulfachlorpyridazine peak area responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Morgan Puderbaugh, B.S.
Associate Scientific Liaison 1-301-998-6833 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4705