The assessment of the stability of the disinfectant “DezA Ultra” and its ready-made solutions during the expected shelf life

High-quality disinfection, a key measure to prevent the spread of infections, is possible only if effective disinfectants are used, which is primarily ensured by the stability of their components. In addition to effectiveness, the stability of a disinfectant also determines the preservation of its antimicrobial activity, safety of use, shelf life, resistance to external factors, expected effect, etc. Under the influence of environmental factors, in particular temperature, humidity, and lighting, processes may occur in unstable disinfectants that lead to changes in their physicochemical properties and, as a result, a decrease in quality. Therefore, stability studies are mandatory to guarantee the effectiveness and safety of disinfectants and their working solutions throughout the entire shelf life. The work aimed to determine the stability of the physical and chemical parameters of the disinfectant “DesA Ultra” and its working solutions during the expected shelf life under the influence of environmental factors and to assess their compliance with the declared characteristics and established standards. According to the results of the conducted research, it was established that the disinfectant “DesA Ultra” series 100121, 120121, and 170121 during the expected shelf life, which was 24 months, was transparent, light yellow, without mechanical inclusions, with a faint specific odor of the components and this fully corresponded to the declared characteristics. The fluctuations in the density, pH, didecyldimethylammonium chloride, benzalkonium chloride and glutaric dialdehyde content detected during the declared shelf life under the influence of environmental factors were at the level of measurement error, did not exceed 10 % and did not go beyond the limits, which were respectively from 1.120 to 1.150 g/cm3, from 3.5 to 6.0, from 6.3 to 7.7 %, from 7.2 to 8.8 % and from 24.3 to 29.7 %. The physicochemical properties of the finished solutions intended for highly dispersed aerosol spraying and for filling disinfectant barriers and wet disinfection of premises and equipment were also stable during the declared shelf life of 7 days, and the content of active substances did not go beyond 10 % of the expected concentrations in the finished solutions. The conducted studies confirmed the proposed two-year shelf life of DezA Ultra and its ready-made solutions for 7 days, provided they are stored in a dry place, away from direct sunlight, at a temperature of 15–35 ℃ and a relative humidity of 45–65 %.