The research used the analysis of modern domestic and foreign scientific literature, the instructions of the American Society for Testing and Materials (ASTM), the International Association of Official Analytical Chemists (OAAC International), state DSTU for sampling solids and liquids. The importance of the sample preparation stage in chemical analysis is noted. In particular, if the samples are taken incorrectly, even if they are properly stored, prepared and analyzed, the researcher will still get false results. However, with the necessary experience and the use of statistical methods, sampling can be performed with the same accuracy as the analysis itself. The peculiarity of sample preparation of solid-phase and liquid samples is considered.
