Anton Paar Digital Density Meters have been used for decades to accurately determine the concentrations of many binary liquids. However, a density measurement is not enough information to calculate quantities in samples containing more than two species. With the addition of a sound velocity measurement, all concentrations of certain ternary solutions can be resolved.
A three-component system consists of a component A with the concentration A, a component B with the concentration B and a solvent (typically water). A few examples of common systems found in production are formaldehyde/methanol/water and silicon dioxide/sodium dioxide/water.