In positive displacement systems, the piston is part of the tip and in direct contact with the liquid. There is no air cushion that may be affected by liquid sample properties. These tools are therefore ideal for liquids with varying viscosity, volatility, surface tension or density as well as hot or cold liquids. The disposable tips with integrated pistons (e.g. Combitips advanced)
also prevent contamination and help to keep user and instrument (Multipette
safe when working with hazardous liquids.