METHOD FOR THE QUANTITATIVE DETERMINATION OF 1,4-DIHYDRO DERIVATIVES OF 1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDE Russian patent published in 2022 - IPC G01N33/15 G01N30/52 

FIELD: chemistry.

SUBSTANCE: method for the quantitative determination of 1,4-dihydro derivatives of 1,2,4-benzotidiazine-1,1-dioxide, including dissolution of the analyzed sample at room temperature and stirring, treatment of the aliquot part of the prepared solution with chemical reagents: SnCl₂ solution in a strongly acidic medium, interaction of the obtained sulfhydryl compounds with sodium nitroprusside in an alkaline solution, followed by photoelectric colorimetry of the obtained colored solutions, quantitative determination of the target substance according to the calibration schedules, characterized in that the exact weights of chlorothiazide, bendrosflumethiazide, benzothiazine, cyclomethiazide or hydrochlorothiazide are dissolved in DMFA, the aliquot part of chlorothiazide, bendrosflumethiazide and benzothiazole, cyclomethiazide or hydrochlorothiazide is treated with a 2-3-fold excess relative to the detectable component of 0.01 Μ SnCl₂ solution in concentrated HCl, and then hot concentrated HCl to create a pH of 4-5 and boil for 20 minutes, then cooled to room temperature temperatures and H₂O is added and hot concentrated HCl in a volume ratio of 1:1 to create a pH of 4-5, they are kept for 2 minutes at a temperature of 30-40°C on a water bath and cooled to room temperature, 0.01 Μ aqueous solution of NaOH is added to a pH of 8-10 and drop by drop, gradually an excess relative to the determined component of an aqueous solution of sodium nitroprusside is added to 0.1 Μ KOH, kept for 2 minutes, 5% aqueous solution (NH₄)₂SO₄ is added as a stabilizer in a volume ratio of 1:30 with respect to an aqueous solution of sodium nitroprusside in 0.1 Μ KOH, the optical density of colored solutions is measured on a photoelectric colorimeter at 490 nm, the comparison solution is a solution of sodium nitroprusside in 0.1 Μ solution of KOH.

EFFECT: expansion of the range of methods for quantitative determination of 1,4-dihydro derivatives of 1,2,4-benzotidiazine-1,1-dioxide.

1 cl, 5 dwg