Mobile phase, Standard solution, and Chromatographic system— Proceed as directed in the test for Limit of free chloramphenicol under Chloramphenicol Sodium Succinate.

Test solution— Dissolve the contents of 1 container in a volume of Mobile phase to obtain a solution containing the equivalent of about 100 mg of chloramphenicol per mL. Dilute this solution quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution containing the equivalent of about 0.5 mg of chloramphenicol per mL. Pass a portion of this solution through a filter having a 0.5-µm or finer porosity, and use the filtrate.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the free chloramphenicol peaks. Calculate the percentage of free chloramphenicol (C11H12Cl2N2O5) in the specimen taken by the formula: in which C is the concentration, in µg per mL, of USP Chloramphenicol RS in the Standard solution; D is the concentration, in mg per mL, of chloramphenicol equivalent in the Test solution, based on the labeled quantity in the container and the extent of dilution; and rU and rS are the chloramphenicol peak areas obtained from the Test solution and the Standard solution, respectively. Not more than 2.0% is found.

(Official January 1, 2007)

Standard preparation— Proceed as directed in the Assay under Chloramphenicol Sodium Succinate.

Assay preparation— Constitute 1 container of Chloramphenicol Sodium Succinate for Injection as directed in the labeling. Dilute an accurately measured volume of the constituted solution quantitatively with water to obtain a solution having a concentration of about 20 µg of chloramphenicol per mL.

Procedure— Proceed as directed in the Assay under Chloramphenicol Sodium Succinate. Calculate the quantity, in mg, of chloramphenicol (C11H12Cl2N2O5), in each mL of the constituted Chloramphenicol Sodium Succinate for Injection taken by the formula: in which L is the labeled quantity, in mg, of chloramphenicol in each mL of constituted solution; D is the concentration, in µg per mL, of chloramphenicol in the Assay preparation, on the basis of the labeled quantity of chloramphenicol in each mL of constituted solution and the extent of dilution; C is the concentration, in µg per mL, of USP Chloramphenicol RS in the Standard preparation; P is the potency, in µg per mg, of USP Chloramphenicol RS; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.