The accurate sensitive analysis of drugs in environmental samples, as well as the removal of these substances from natural and waste waters, is the great importance for maintaining viability. Sulfaguanidine is a widely used antibiotic. Registration of absorption and fluorescence spectra, spectra of pulsed cathodoluminescence in the region from 350 to 900 nm under irradiation with electron beams with a duration of 2 ns and an average energy of 170 keV was carried out to study the transformation of sulfaguanidine in water. It has been shown that this treatment of the solution results in the transformation of the sulfaguanidine molecule. Irradiation of the solution and excitation of pulsed cathodoluminescence of the boundary layer of air localized near the surface of the solution were carried out simultaneously by the same electron beam. The degree of antibiotic transformation under the action of an electron beam was determined from the change in the luminescence and absorption spectra of the irradiated solution. As a result, we recorded the utilization of dissolved sulfaguanidine, which means the neutralization of the solution. Thus, after electron irradiation, the toxicological effects of sulfonamide antibiotics decrease.

Sulfonamides are one of the oldest groups of veterinary chemotherapeutic agents. Physico-chemical properties, the concentration and the nature of the environment are the factors responsible for the distribution of sulfonamides in the living organism. Although these drug compounds have been in use for more than half a century, knowledge about their behavior is still limited. Physiological activity is currently attributed to the sulfanyl radical. Our study is devoted to the spectral properties of aqueous solutions of sulfaguanidine, in which the formation of complexes with an H-bond and a protonated form takes place. The nature of the fluorescent state of sulfaguanidine was interpreted using computational chemistry, the electronic absorption method and the luminescence method. The structure of sulfaguanidine includes several active fragments: aniline, sulfonic and guanidine. To reveal the role of fragments in the physiological activity of the studied antibiotic, we calculated and compared the effective charges of the fragments of aniline and sulfaguanidine molecules. Chromophore groups were identified in molecules, which determine the intermolecular interaction between a molecule and a proton-donor solvent. The study also revealed the impact of sulfone and guanidine groups, as well as complexation, on the effective charge of the antibiotic fragment responsible for physiological activity and luminescent ability.

The absorption and fluorescence spectra of sulfaguanidine, its complexes with hydrogen bonds, and doubly charged cationic forms have been studied experimentally and theoretically. The orbital nature of electronically excited states is established and a theoretical interpretation of the absorption and fluorescence spectra is given. It was shown that the main reason for the anomalously large Stokes shift of fluorescence is the rearrangement of the benzoid structure of the phenyl fragment of sulfaguanidine into a quasi-quinoid one. The influence of the formation of hydrogen bonds and the addition of a proton on the amount of charge transfer between weakly bound fragments of the molecule has been established Keywords: sulfaguanidine, sulgin, absorption spectra, fluorescence, quantum chemical calculation.