Supplementation of microelements (Mn, Zn, Cu, Cr) to livestock diet is of particular concern. There are various mineral feed additives available on the market. The most frequently used are inorganic feed additives, characterized with low bioavailability and high toxicity. Also, organic feed additives are used, including amino acids chelates, in which bioavailability was greatly improved and toxicity reduced. The problem is high price of these products. Therefore, there is the need to search for new biological mineral feed additives with designed composition, that would be characterized with high bioavailability, low toxicity, low cost and that would also possess a nutritional value. Such a possibility offers biological materials. It was found that biomaterials have metal-binding capabilities. Metal ions may be bound to biomass via either biosorption or bioaccumulation process. When elaborating technology of the production of feed additives, containing simultaneously various elements, it is necessary to use the tool of multielemental analysis in order to simultaneously analyze the content of Mn, Zn, Cu, Cr. In the present work, ICP-OES multielemental analysis was used to investigate the process of production of mineral feed additives based on the biomass of aquatic plant Lemna minor. The effectiveness of the processes of biosorption and bioaccumulation of microelements by an aquatic plant L. minor was studied. The mechanism of the process as well as equilibrium was investigated with the use of multielemental analysis by ICP-OES Vista-MPX instrument from Varian (Australia).