The origin of Ultra High Energy Cosmic Rays is still unknown, and Active Galactic Nuclei (AGN) have been proposed as candidates to accelerate these particles. The aim of our work is to test the model of the particle acceleration in the hotspots of the AGNs. Using the multi-wavelength data of radiogalaxy 3C 105 S we calculate the maximum achievable energy of the cosmic rays through via the diffusive-shock acceleration (DSA) mechanism. We consider that the magnetic field in the jet termination region (hotspot) is amplified by the Bell instabilities. We find that maximum energy hat particles can achieve in the hotspots of radiogalaxy 3C 105 is well below the energy of Ultra High Energy Cosmic Rays.