COMPREHENSIVE USE OF GAS CHROMATOGRAPHY-MASS SPECTROMETRY AND DISSOCIATIVE ELECTRON ATTACHMENT SPECTROSCOPY METHODS TO DETERMINE THE ISOMERIC COMPOSITION OF SAMPLES

Due to the fact that in environmental and biomedical sciences there is an ever-growing need to detect traces of toxins (xenobiotics) and analyze specific target substances in complex test samples, various types of equipment related to analytical chemistry are growing and multiplying. The paper shows the possibility of using gas chromatography-mass spectrometry and spectroscopy of dissociative electron attachment in conjunction with quantum mechanical calculations using the density functional theory method to refine the results of the analysis of the isomeric composition of the studied samples. This is achieved due to the fact that substances with overlapping chromatographic peaks are distinguished by their mass spectra, and isomers with similar or identical mass spectra are distinguished by retention indices and resonances arising on the curves of effective electron yield during dissociative electron attachment. The main difference between the isomers of phthalide and itself was that they did not form negative molecular ions. Impurity molecules were detected in the studied samples. Chromatographic analysis and analysis of the mass spectra of positive ions suggested candidates for this role. By comparing the data obtained with the spectra of dissociative electron capture and calculated thermodynamic thresholds for the formation of fragmentary ions, it was possible to more accurately determine the composition of the impurity.