The technique of overspills analysis after classification for content of non-ferrous metals has been improved at beneficiation plant of “Kola mining metallurgical company”. Discrepancies not meeting the requirements of GOST 14180–80 standard in operation of automatic sample-collecting devices and divider of 1^st, 2^nd and 3^rd sections has been eliminated, variation coefficients have been defined experimentally whereby the category of homogeneity of overspills after classification has been established and required characteristics of operation of the equipment for sample collection and preparation have been defined and imprecision of analysis have been established experimentally. The technique of measurement compensation has been developed by the Federal agency for technical regulation and metrology.