With the aim of study possible mechanical trapping phenomena and adsorption in a double porosity medium we performed two types of experiments: 1) A saline polymer solution which initially saturates a porous medium is displaced with another polymer solution with a different salt concentration (conductivity measurement). In both solutions the polymer used is scleroglucane. 2) A flow of a saline solution into a polymer solution (scleroglucane), which initially saturates the porous media of double porosity (conductivity measurement). At the same time, a flow of a polymer solution marked with a radioactive tracer (gamma emitter) is performed and its displacement can be followed externally to the medium. In both cases, the dispersion profile at the outlet and at each position along the medium are analyzed. The polymer solution rheology was carefully controlled: it is a shear thinning fluid with n=0.6, while ensuring the absence of microgels in the solution. The porous medium was prepared with an homogeneous poral size distribution, with grains of 500 micrometers diameter and an internal porosity of 30 percent, obtained by grinding sintered glass beads. The experiments were performed with the medium in vertical position. The first results suggest that the saline solution explores all the poral structure while it is possible that the macromolecules of the polymer solution cannot penetrate into the small pores. With these experiments we expect to obtain information about the presence of heterogeneities in the bed. However, this information was obtained only in those cases where we change the concentration of the polymer solutions. Finally, we can observe a retention phenomenon, whose interpretation is still controvertible.