Calcium carbonate, a white-colored powder with thechemical formula CaCO3, is widely used in manyapplications which can be found all around us. Forinstance, one of its most obvious applications is its useas the principal ingredient of chalk. However, calciumcarbonate is also widely used in rubbers and plastics,paper and tooth powder, etc. as a filling material.When measuring the infrared spectrum of rubber thatcontains calcium carbonate, a large calcium peakmasks peaks originating from some of the rubberconstituents, which could cause difficulties in qualitativeanalysis. Here we introduce a pretreatment method forremoving the calcium carbonate from rubber thatcontains calcium carbonate.