The MicroPlastic Sediment Separator (MPSS) is a device which enables the separation of microplastic particles from large sediment volumes. It is based on the principle of density separation which exploit the fact that plastic particles have lower density than sediments grains by mixing the sediment sample with a separation fluid. The sediments sink to the bottom while the low-density plastic particles float and can be retrieved. The MPSS is divided into compartments made of stainless steel. At the top a sample chamber allows the recovery of the floating plastics.