Koepitoisuuden

Koepitoisuus (Finnish for test concentration) refers to the concentration of a chemical or substance used in a specific test, assay, or experiment. It represents the intended level applied during the procedure and is a central parameter in experimental design. The concept is used across fields such as pharmacology, toxicology, microbiology, and analytical chemistry to study dose–response relationships, efficacy, toxicity, and detection limits.

How koepitoisuus is determined and prepared. Researchers select koepitoisuus based on prior knowledge of the substance’s activity, solubility, stability, and the sensitivity of the assay. It is commonly expressed in units such as molarity (M, mM), mass per volume (mg/L), or volume per volume. Stock solutions are prepared and serial dilutions are made to create a range of test concentrations, often including negative controls (no substance) and positive controls.

Measurement and reporting considerations. During reporting, the koepitoisuus should be documented as the nominal concentration applied to the test system. Depending on the context, the realized concentration may differ due to factors such as degradation, binding to surfaces, or adsorption; these should be considered when interpreting results. In many protocols, both nominal and measured concentrations are reported.

Contexts and examples. Common applications include in vitro drug screening, where cells are exposed to multiple koepitoisuuksia to generate a dose–response curve; environmental testing to assess toxicity at defined concentrations; and enzyme assays where substrate or inhibitor concentrations are specified. The term is especially common in Finnish scientific writing; in international contexts it is often translated as “test concentration” or “assay concentration.”