Small angle grain boundaries have been grown in a small Bridgman furnace, using seeded growth method, at three different pulling rates i.e. 3 μm/s, 13 μm/s and 40 μm/s. In order to assess segregation mechanisms of impurities towards the central grain boundary, melt has been polluted by 50ppma of either copper or indium. Secondary ion mass spectrometry (SIMS) local analyses have been performed to investigate the impact of solid state diffusion and limited rejection of solute at the grain boundary for each growth rate. The results are discussed in connection with an atomistic model built on Vienna Ab-initio Simulation Package (VASP).