The type of filter holder, the pore size, porosity, area, and thickness of the filter and the physical nature, particle size, and amount of material deposited on the filter are the principal factors affecting separation of suspended from dissolved solids. “Dissolved solids” is the portion of solids that passes through a filter of 2.0 ไมโครเมตร (or smaller) nominal pore size under specified conditions. “Suspended solids” is the portion retained on the filter.