Most of the Penning trap spectrometers for precision measurements at radioactive ion beam facilities make use of another Penning trap, located upstream in the experimental set up, to perform isobaric separation and deliver cooled and pure ion samples to be measured. The preparation trap for the project TRAPSENSOR at the University of Granada has been built to prepare ions, produced off-line with a laser-desorption ion source, using firstly the buffer-gas cooling technique. The system has been built following the geometrical specifications given in the Technical Design Report for the MATS Penning-trap system to be built at the future Facility for Antiprotons and Ion Research (FAIR) in Darmstadt. So far, cooling resonances have been obtained for stable nuclides, with mass-to-charge ratios ranging from 40 to about 200, with a performance similar to those systems already in operation at radioactive ion beam facilities. In this contribution, the preparation trap, built and commissioned at the University of Granada, will be briefly described. First results on buffer-gas cooling will be presented.