Specimen matrix

Matrix effects can change how a test performs, so performance studies need to cover each claimed matrix. Matrix comparison studies are a common way to support adding a new one.

Medium or milieu in which the analyte of interest may be contained (e.g., cerebrospinal fluid, serum, blood, other tissue, or viral transport media). The discrete portion of a body fluid or tissue taken for examination, study, or analysis for one or more quantities or characteristics.

FDA guidance: Design Considerations for Pivotal Clinical Investigations for Medical Devices (November 2013), Section 11, Glossary