Development of a Quantitative Determination Technique for Ascorbic Acid in Medicines.

A coordination compound of iron(III) ion with 1,10-phenanthroline, or the oxidized form of ferroin (OFF), which was obtained via the reaction of phenanthroline hydrochloride and iron(III) ammonium sulfate (3:1) in acidic solution and standardized by indirect iodometry, was proposed for use as a titrant for quantitative determination of ascorbic acid (AA) in drugs. The developed method for determining AAwas characterized by satisfactory validation indicators of specificity, linearity (r = 0.990), extended analytical range (50 – 170% AA), accuracy (AA recovery 99.6%), precision (RSD 1.3%), and low relative error of determination (å 2.9%). The procedure for AA analysis using OFF did not depend on the solution pH and ionic strength and enabled titrations in colored and cloudy solutions. The technique was tested on various commercial drugs: 5% AAsolution for injection, Revit drops, AA tablets with glucose, and cinnamon rose hips. [ABSTRACT FROM AUTHOR]