interferentssubstances

Interferent substances, commonly called interferents, are compounds or particles that distort analytical measurements or diagnostic results by reacting with reagents, altering signals, or affecting sample properties. They can be present in the sample matrix, introduced during collection, or come from reagents and the environment.

Common forms include chemical interference (reaction with reagents), spectral interference (absorbance or fluorescence overlapping with analyte signal), physical interference (viscosity, turbidity, particle scattering), and biological interference (endogenous substances in biological samples such as lipids, bilirubin, hemoglobin). Instrumental interference can also occur (ion suppression in mass spectrometry, baseline drift).

Sources include natural sample constituents (urine, blood), dietary components, medications, exogenous contaminants, or improper sample handling. Examples: bilirubin causing colorimetric assay bias; hemoglobin causing spectral shifts; heterophile antibodies causing immunoassay false results; co-eluting compounds causing ion suppression in LC-MS.

Mitigation strategies include sample preparation and cleanup, dilution, or separation techniques; choosing alternative assays or columns; using matrix-matched calibration or standard addition; employing internal standards; and validating methods under realistic matrix conditions.

Quality control and method validation should assess potential interference via interference studies, recovery experiments, and robustness testing. Reporting typically notes known interferents and limitations of the method.