ttps://doi.org/10.22184/2227-572X.2022.12.5.360.369

The content of the active substance in pharmaceutical substances is determined in terms of an anhydrous and free from residual organic solvents (RS) substance. The State Pharmacopoeia of Russian Federation regulates thermogravimetry and Karl Fischer titration for measuring water content and thermogravimetry and gas-liquid chromatography with flame ionization detection for measuring RS content. These methods have limitations in applicability and measurement results may be unreliable. The article considers alternative methods and describes the results of their testing as basic or additional. More than 30 pharmaceutical substances were analyzed using air-thermal drying, volumetric titration according to Karl Fischer method described in the State Pharmacopoeia of Russian Federation. To refine the results, the methods of thermogravimetric analysis with mass spectrometric detection (TGA-MS), high-performance liquid chromatography in combination with diode array detection (HPLC-DAD) and gas-liquid chromatography with mass spectrometric detection (GLC-MS) were used. The complex use of various methods on the example of the analysis of azithromycin dihydrate, cyanocobalamin, triphenylmethanol and (RS)-3-(naphthalene 1 yloxy)propan 1,2 diol was allowed to clarify the composition of impurities and conduct their quantitative assessment. Thus, the use of the described methods makes to increase the reliability of determining water and RS in the analysis of pharmaceutical substances.