DEVELOPMENT OF A METHOD FOR GAS-CHROMATOGRAPHIC DETERMINATION OF ETHANOL IN DICLOFENAC GEL AND ITS VALIDATION
Diclofenac is the most widely used non-steroidal anti-inflammatory drug. The development of a method for gas chromatographic determination of ethanol as an auxiliary component of a new dosage form (generic) "Diclofenac gel for external use 5%" and its validation. The working conditions for the gas chromatographic determination of ethanol were established using a DB-5 capillary column 30 m long, 0.53 mm in diameter (5% phenyl - 95% methylpolysiloxane), with a stationary phase layer thickness of 5.0 μm; nitrogen at a flow rate of 2.5 ml / min, a temperature gradient and a flame ionization detectorThe efficiency of the chromatographic column calculated from the ethanol peak (retention time 4.33 min) on the ethanol solution chromatogram is 12,000 theoretical plates; the asymmetry factor of the ethanol peak on the chromatogram is 1.33; the standard deviation of the ethanol peak areas is not more than 2.0% (n ≥ 5). For a quantitative assessment of the interfering effect of the components of the gel, solutions were prepared from a weighed portion of placebo, containing all the components, except for the analyte. The calibration dependence is linear and is described by a regression equation with a correlation coefficient of 0.99923. The assessment of the correctness was carried out at three levels of concentration of ethanol in solution (2.4 mg / ml, 3 mg / ml, 3.6 mg / ml) with three parallel determinations of each concentration. As a result of testing for all indicators, values were obtained that meet the stated criteria. The technique allows obtaining reproducible, reliable results and was tested for the quantitative determination of ethanol in samples of the drug “Diclofenac gel for external use 5%".