Determination of quaternary ammonium salts and polyhexamethylene biguanide hydrochloride in the coexistence in disinfectants and their biocidal activity

Titrimetric methods for determining the concentration of quaternary ammonium salts and polyhexame­thylenebiguanide hydrochloride in the presence of a disinfectant are described. In addition, as auxiliary components, the agent contains a nonionic surfactant and an alkyl polyglucoside and a disodium salt of ethylenediaminetetraacetic acid as a complexing agent. The main differences between the methods proposed by us for the determination of quaternary ammonium salts and polyhexamethylenebiguanide hydrochloride is the use of not sodium dodecyl sulfate as a titrant, but a solution of the disinfectant itself, which greatly facilitated the visual fixation of the equivalence point. In addition, the volume of the indicator (methylene blue and bromophenol blue) was selected in such a way that the exposure between the portions of the added titrant was not prolonged, because this would increase the overall duration of the analysis. When titrating with polyhexamethylenebiguanide hydrochloride, the vo­lume of the indicator is selected in such a way as to minimize the interfering effect of HR, which are also part of disinfectants. The reproducibility of the developed methods has been confirmed in accredited laboratories of the relevant state institutions of the Republic of Belarus. Metrological characteristics of the developed methods: accuracy index±3.7 %, reproducibility index 4.0 %, n = 17, P = 0.95 – to determine the QAS; accuracy index±4.2 %, reproducibility index 5.5 %, n = 17, P = 0.95 – for the determination of PHMBG.