quantificatielimiet

Quantificatielimiet, or the limit of quantification (LOQ), is the lowest concentration of an analyte in a sample that can be quantified with acceptable accuracy and precision under predefined conditions. It is an essential parameter in analytical method validation because it defines the practical lower bound of reliable measurements for routine reporting.

The LOQ is related to, but distinct from, the limit of detection (LOD). The LOD is the smallest amount that can be detected but not necessarily quantified, whereas the LOQ requires that the measurement be both detectable and quantitatively reliable. In many methods, the LOQ is higher than the LOD to ensure that reported values meet predefined quality criteria.

Common approaches to determine the LOQ include a signal-to-noise method and a precision-based method. The signal-to-noise approach often uses a criterion such as a signal ten times the baseline noise. The precision-based approach relies on calibration data or replicate analyses to establish the lowest concentration at which a predefined relative standard deviation or coefficient of variation (for example, 15–20%) is achieved. In practice, the LOQ is method- and matrix-dependent and should be established during method validation for each specific sample type or matrix.

LOQ is widely used across fields such as environmental monitoring, clinical chemistry, pharmacology, food safety, and forensic analysis. It informs reporting limits, validation requirements, and regulatory compliance. Because it depends on instrumentation, sample preparation, and matrix effects, the LOQ should be periodically reevaluated when method conditions change.