A modification method of the target for Matrix Assisted Laser Desorption/Ionization (MALDI) analysis by metal-affinity sorbents was proposed. Monolayers of metal stearates obtained in the geometry of the drop perform as such sorbents. The formation of monolayers was proved by optical microscopy and the Laser Desorption/Ionization (LDI) method. The surface of the substrate after modification studied using scanning electron microscopy. Metal-affinity extraction of human serum albumin adducts with soman was carried out at the modified target surface. MALDI mass spectrometric analysis demonstrated that signals corresponding to adducts are present in mass spectra.