METHOD FOR QUANTITATIVE DETERMINATION OF PHENOBARBITAL IN “CORVALOL” TABLETS BY UV SPECTROPHOTOMETRY USING THE SPECIFIC ABSORPTION INDEX Russian patent published in 2018 - IPC G01N33/15 G01N21/00 

FIELD: chemistry.

SUBSTANCE: invention relates to analytical chemistry, namely to pharmaceutical analysis, and can be used to quantify phenobarbital in “Corvalol” tablets by UV spectrophotometry. For this purpose absorbance of a standard sample (SS) solution of phenobarbital is measured at a wavelength of 240±2 nm in a cuvette with a layer thickness of 10 mm, as a result, the value of the specific absorption index of phenobarbital = 457, which is used to calculate the concentration of phenobarbital in solution in %. Test solution is obtained by dissolving Corvalol tablets in 600 ml of water for 45 minutes at a basket rotation speed of 100 rpm. Optical density of the test solution is then measured on a spectrophotometer as above, a solvent is used as the reference solution. Amount of phenobarbital (C₁₂H₁₂N₂O₃), which has passed into the solution from the tablet, is calculated taking into account the declared content of phenobarbital in the tablet.

EFFECT: invention provides quantitative determination of the active substance without the use of standard phenobarbital samples.

1 cl, 2 tbl, 1 dwg, 1 ex