USP Monographs Azithromycin - USP 43 - NF 37
Azithromycin is anhydrous or contains 1 or 2 molecules of water of hydration. It contains the equivalent of NLT 945 µg/mg and NMT
If a difference appears in the IR spectra of the analyte and the Standard, dissolve equal portions of the test specimen and the USP Reference Standard in equal volumes of methanol. Evaporate the solutions to dryness on a water bath, and dry at 80° for 30 min under vacuum. Perform the test on the residues.
The retention time of the azithromycin peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.