Stoffinhalt

Stoffinhalt is a German term used to describe the amount or proportion of a substance contained in a system, mixture, or product. It denotes how much of a particular chemical component is present and can refer to mass, volume, or amount of substance, depending on context. In chemistry and materials science, the Stoffinhalt may be expressed as mass fraction, volume fraction, or molar content. Common expressions include weight percent, volume percent, or concentration, while in labeling the term often corresponds to the explicit quantity of the active substance.

In practice, the Stoffinhalt is determined by measurement and calculation. For a mixture with total mass m_tot and a component with mass m_i, the mass fraction is w_i = m_i / m_tot × 100%. In a solution, the amount of substance can be reported as mass, molar amount, or molar concentration. For pharmaceuticals, a tablet might list a Stoffinhalt of 500 mg of the active pharmaceutical ingredient per tablet. In fuels, the Stoffinhalt of a solvent or additive is given as a percentage of the total composition.

Terminology notes: Stoffinhalt is not always used precisely in technical standards; terms such as Gehalt, Gehalteanteil, Konzentration, or Anteil are more common in specific fields. The exact meaning should be inferred from the accompanying units or context.