We chose to develop and test our own version of the osmostat in RASPA to have access of functionalities already implemented in the software for studying adsorption of electrolytes solutions in nanoporous materials. We plan to use our osmostat to simulate adsorption of various electrolyte solutions in zeolithes or MOFs that requires calibration of osmostat of different electrolytes solution over a wide range of concentration, which was the main goal of the current work. This opens the route for probing thermodynamics of electrolyte intrusion, pression intrusion and structure of intruded electrolyte solution in nanoporous material which will be the object of the next study. However, because of the choice of our empirical force field that is not optimal for divalent cations, we do not focus on reproducing precisely the structure of divalent cation electrolytes although we expect to grasp the thermodynamics and thus concentration of divalent cation electrolyte in porous materials. In addition, a version of RASPA with implementation of the osmostat will be provided therein. As a last remark, the osmostat was tested on relatively small boxes of monovalent or divalent-cation aqueous electrolytes as a proof-of-concept because RASPA is a sequential program and it would be time consuming to consider larger systems. In this regards, zeolites/MOFs are in most cases periodic so that only a supercell of several repeating units is required for future MC simulations where only few hundreds of free particles are adsorbed which is fortunately feasible with RASPA.