QUANTITATIVE DETERMINATION ALGORITHM OF ACETYLSALICYLIC ACID BY FTIR SPECTROMETR

Introduction. The article presents an algorithm for the quantitative determination of acetylsalicylic acid by Fourier-transform infrared (FTIR) spectroscopy in the mode of disturbed total internal reflection on the example of the analysis of mixtures similar to the composition of tablet dosage form. The study aims to develop an algorithm and a mathematical model based on the partial least squares (PLS) method. The proposed algorithm allows to exclude the stage of dissolution of samples, reduce the analysis time and can be adapted for the quantitative determination of other organic substances in solid dosage forms. Objective. Development and approbation of an algorithm for the quantitative determination of acetylsalicylic acid in solid multicomponent mixtures using FTIR-spectrometry with a mathematical model based on the partial least squares method. Material and Methods. The study was carried out on a model mixture of tablet mass, similar of tablets “Acetylsalicylic acid” 500 mg (OJSC “Dalchimpharm”). 30 calibration and 15 control samples were prepared by mixing acetylsalicylic acid substance with a mixture of excipients. IR spectra were recorded on a Cary 630 FTIR spectrometer (Agilent, USA) in the range of 4000-650 cm-¹ (resolution: 4 cm-¹). Data were processed in KNIME 4.5.7 using the Python 3.9.10 package and the scikit-learn 1.3.0 library. Processing stages: normalization, multiplicative scattering correction, separation of spectrometric data into training/test sets (in the ratio 70:30 according to the Kennard-Stone method), obtaining a calibration (“mathematical”) model by the PLS method, testing the predictive ability of the model on the test set, and testing the model on control samples of acetylsalicylic acid. Results. The determination coefficient (r²) of the mathematical model when analyzing the test sample of spectrometric data was 0.97, which confirms its high predictive ability. When tested on control samples of acetylsalicylic acid, the relative deviation of the calculated concentration from the actual one did not exceed ±5%. Conclusions. An algorithm for the quantitative determination of acetylsalicylic acid by infrared spectrometry in the mode of disturbed total internal reflection based on the partial least squares method was developed and tested. The relative deviation of ±5% in a wide range of concentrations indicates the applicability of the algorithm for the development of a technique for the quantitative analysis of acetylsalicylic acid by FTIR-spectrometry. Further optimization of spectrometric data processing in order to increase the predictive ability of mathematical models will allow to implement the algorithm in quality control of tablet dosage forms.