The presence of different MT isoforms contributes to the functional diversity of these proteins and enables organisms to adapt to various environmental stressors and toxic substances. The identification and characterization of these isoforms are essential for understanding their specific roles in biological processes, as well as for assessing the effects of environmental factors on organisms and ecosystems. Therefore, the primary objective of this study will be to separate MT isoforms in the digestive gland of bivalves using a two-step chromatographic approach: first, separation of MTs by size-exclusion chromatography, followed by separation of the isoforms using an anion-exchange chromatography column. An additional objective will be to determine the amino acid composition of each MT isoform and to identify the fundamental differences among them. The identification of different MT isoforms may provide further insight into the mechanisms of organismal detoxification and contribute to the assessment of environmental pollution levels and the ecological sustainability of their habitats. Furthermore, understanding the functions of MT isoforms may facilitate the development of novel biomarkers for monitoring environmental pollution and evaluating the effectiveness of environmental protection measures. The final objective of this research will be to determine the molecular mass and amino acid sequence and to identify MT isoforms using two mass spectrometry techniques, MALDI-TOF-MS and LC-MS/MS. The proposed objectives will be achieved through the application of modern analytical methodologies, the optimization of existing methods, and the development of optimal conditions for conducting the required analyses.