METHOD FOR QUANTITATIVE DETERMINATION OF BENZOTHENOTHIAZINE-1,1-DI-OXIDE DERIVATIVES (OXICAM GROUPS) Russian patent published in 2021 - IPC G01N33/15 

FIELD: medicine; pharmaceuticals.

SUBSTANCE: invention relates to pharmaceutical analysis, specifically to analysis of materials using optical means, and can be used for quantitative determination of benzothenothiazine-1,1-dioxide (oxycam group) derivatives, namely lornoxicam (I), meloxicam (II), tenoxicam (III), piroxicam (IV) and tianeptine (V) in substances. Method for quantitative determination of benzothenothiazine-1,1-dioxide (oxyxam group) derivatives involves dissolving the analysed sample in DMF, holding until complete dissolution at room temperature, stirring, treatment of an aliquot part of the prepared solution first with a solution of a reducing agent, and then alkaline solution of sodium nitroprusside with subsequent photoelectric colorimetry of coloured solutions. Precise weighed portions of lornoxicam, meloxicam, tenoxicam, piroxicam and tianeptine are dissolved in graduated flasks in DMF. 0.01M tin (2+) chloride solution and hot concentrated hydrochloric acid are added in excess to the aliquot part of the substances. One boils for 30 minutes. After cooling, water and hot concentrated hydrochloric acid are poured to pH 4–5, held for 2–3 minutes at temperature of 30–40 °C and cooled. Alkali solution is added to the obtained sulphides to pH 6–10 and an excess of alkaline solution of sodium nitroprusside is gradually added drop by drop, held for 2 minutes. Appears orange colouring, stable for 2 hours. To preserve stability of obtained reaction products, ammonium sulphate solution is added, optical density of coloured solutions is measured at wave length of 364 nm.

EFFECT: invention provides accessibility, high accuracy of determination, sensitivity, selectivity, absence of use of toxic reactants and reaction products.

1 cl, 5 dwg