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» Chlortetracycline Bisulfate has a potency equivalent to not less than 760 µg of chlortetracycline hydrochloride (C22H23ClN2O8·HCl) per mg, calculated on the dried and butyl alcohol-free basis.
Packaging and storage Preserve in tight, light-resistant containers.
Labeling Label it to indicate that it is intended for veterinary use only.
USP Reference standards 11
Identification, Ultraviolet Absorption 197U
Solution: 40 µg per mL.
Medium: 0.1 N hydrochloric acid.
Absorptivity at 368 nm, calculated on the dried and butyl alcohol-free basis, is not less than 83.0% and not more than 95.0% of that of the USP Chlortetracycline Hydrochloride RS, the potency of the Reference Standard being taken into account.
Crystallinity 695: meets the requirements.
Loss on drying 731 Dry it in vacuum at a pressure not exceeding 5 mm of mercury at 60 for 3 hours: it loses not more than 2.0% of its weight.
Sulfate content Transfer about 1 g, accurately weighed, to a 250-mL beaker, and dissolve in about 100 mL of water. Neutralize the solution with 7.5 N ammonium hydroxide to litmus paper, and warm. Filter, and wash the filter with warm water. Neutralize the filtrate with 6 N hydrochloric acid to litmus, and add an additional 4 mL of 6 N hydrochloric acid. Heat the solution to boiling, and add, with constant stirring, sufficient boiling barium chloride TS to precipitate all of the sulfate. Add an additional 2 mL of barium chloride TS, and digest on a steam bath for 1 hour. Filter the mixture through ashless filter paper, transferring the residue quantitatively to the filter, and wash the residue with hot water until no precipitate is obtained when 1 mL of silver nitrate TS is added to 5 mL of washing. Transfer the paper containing the residue to a tared crucible. Char the paper, without burning, and ignite the crucible and its contents to constant weight. Perform a blank determination concurrently with the test specimen determination, and subtract the weight of residue obtained from that obtained in the test specimen determination to obtain the weight of residue attributable to the sulfate content of the specimen: not less than 15.0% is found, calculated on the dried and butyl alcohol-free basis.
Ceric ammonium nitrate solution Dissolve 20 g of ceric ammonium nitrate in 4 N nitric acid to obtain 100 mL of solution.
Standard preparations Transfer about 3 g of butyl alcohol, accurately weighed, to a 1000-mL volumetric flask containing 800 mL of water, shake to dissolve, dilute with water to volume, and mix (Standard preparation 1). Transfer 10.0 mL of Standard preparation 1 and 1 drop of dimethicone to a 50-mL distilling flask equipped with a condenser and an extension that reaches into a collecting tube maintained in an ice-water bath. Distill slowly, and collect about 8 mL of distillate. Warm the distillate to ambient temperature, and transfer with the aid of water to a 10-mL volumetric flask. Dilute with water to volume, and mix (Standard preparation 2).
Test preparation Transfer an accurately weighed specimen, equivalent to about 30 mg of butyl alcohol, to a 50-mL distilling flask equipped with a condenser and an extension that reaches into a collecting tube maintained in an ice bath. Add 25 mL of water and 1 drop of dimethicone to the distilling flask. Distill slowly, and collect about 8 mL of the distillate. Warm the distillate to ambient temperature, and transfer with the aid of water to a 10-mL volumetric flask. Dilute with water to volume, and mix.
Procedure To four separate test tubes add, respectively, 5.0 mL of Standard preparation 1, 5.0 mL of Standard preparation 2, 5.0 mL of Test preparation, and 5.0 mL of water to provide a blank. To each add 2.0 mL of Ceric ammonium nitrate solution, and mix. Concomitantly determine the absorbances of the solutions from the Standard preparations and the Test preparation at the wavelength of maximum absorbance at about 475 nm, with a suitable spectrophotometer, using the blank to set the instrument to zero. In a suitable determination, the absorbance of the solution from Standard preparation 2 is not less than 98.0% of the absorbance of the solution from Standard preparation 1. Calculate the percentage of butyl alcohol in the specimen taken by the formula:
1000(WS / WU)(AU / AS)in which WS is the weight, in g, of butyl alcohol taken to prepare Standard preparation 1, WU is the weight, in mg, of specimen taken, and AU and AS are the absorbances of the solutions from the Test preparation and Standard preparation 2, respectively: not more than 15.0% is found.
Assay Proceed with Chlortetracycline Bisulfate as directed for chlortetracycline under AntibioticsMicrobial Assays 81.
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USP35NF30 Page 2646