METHOD FOR QUANTITATIVE DETERMINATION OF ASCORBIC ACID IN DRUGS Russian patent published in 2019 - IPC G01N33/15 

FIELD: medicine; pharmaceuticals.

SUBSTANCE: group of inventions relates to pharmaceutics and can be used to determine quantitative content of ascorbic acid (AA) in drugs. To this end, a solution of an oxidised form of ferrogen (OFF) with concentration of 0.02 mol/l is prepared by dissolving reagent batches: 14.0820 g of phenanthroline hydrochloride monohydrate and 9.6440 g of iron (III) ammonium sulphate dodecahydrate in 100 ml of purified water

and 25 ml of 10 % solution of sulphuric acid in measuring flask with capacity of 1 l with bringing volume of solution with water purified to mark. Titre of OFF solution is set by potentiometric titration with sodium thiosulphate solution on "pH-340" instrument with fixation of electromotive force values of electrochemical cell (E°, mV) depending on volume of titrant (V_T, ml). Titration curves are plotted and titration jump V_T is determined in equivalence point. Also disclosed is a method for quantitative determination of AA in a drug substance.

EFFECT: group of inventions provides higher accuracy of quantitative determination of AA in drugs by redox titration using titrant OFF and potentiometric method of fixing equivalence point.

2 cl, 4 dwg, 11 tbl, 5 ex