The purpose of the article is to develop a technique for determining mass fraction as a necessary and important stage of a reliable forensic assessment of research results based on theoretical generalizations and the practice of complex application of gravimetric and titrimetric methods of analysis using the example of a three-component sulfuric and hydrochloric acids mixture in an aqueous solution. The reliability of the obtained results and conclusions is ensured by the use of general scientific and special research methods. In particular, theoretical methods (analysis, synthesis, comparison, generalization) systematized the materials that constitute the theoretical basis of the study, empirical (observation, measurement, comparison, experiment) experimental studies were conducted to clarify the feasibility of using gravimetric and titrimetric methods of analysis when determining mass particles of inorganic acids. With the help of special statistical and mathematical research methods, both the mass fraction of the constituents of the studied mixtures and the research error were calculated. In general, the application of a complex of methods made it possible to reach a conclusion about the suitability of gravimetric and titrimetric methods of analysis for determining the content of inorganic acids in three-component mixtures. Scientific novelty. The possibility of the complex application of gravimetric and titrimetric methods of analysis to determine the mass fraction of two strong acids (sulfatic and hydrochloric) in an aqueous solution in a three-component mixture is substantiated as a necessary and important stage of a reliable forensic evaluation of research results. Conclusions. Complex application within the experiment of gravimetric and titrimetric methods of analysis to determine the mass fraction in a three-component mixture of two strong acids (sulfate and chloride) in an aqueous solution confirmed the possibility of their use for solving expert tasks. The main advantages of the gravimetric and titrimetric methods of analysis proposed for use are the availability of equipment, simplicity, manufacturability, sufficiently high accuracy, which prove the feasibility of their use for determining individual concentrations of inorganic acids in order to solve the issue of taking measures to control their circulation. The basic principles of the methodology for determining the content of sulfuric and hydrochloric acids in a three-component mixture are outlined, which will serve as a basis for the further development of methodological recommendations in this direction. In addition, the selection of the main parameters of the reagents was carried out and a method was proposed for the quantitative analysis of individual components (inorganic acids) of mixtures (solutions) - sulfuric and hydrochloric acids in a three-component mixture, which is based on their sequential separation and allows obtaining the value of their mass fraction with relative errors 2.4% for sulfate and 4.6% for chloride, which is within the permissible measurement error (Δхmax ≤ 3σ).
Keywords: forensic examination; precursors; sulfuric acid; hydrochloric acid; gravimetric method of analysis; titrimetric method of analysis; the mass fraction.
