What is the term for a substance that is being identified or measured in a lab test?

• A. Reagent
• B. Sample
• C. Analyte
• D. Calibrant

Answer: (C)

The substance being identified or measured in a lab test is called the analyte. In any assay, the goal is to determine how much of a specific chemical, biomolecule, or compound is present, and that target is the analyte. The sample is the material you collect to test, which may contain the analyte among other things. A reagent is the chemical used to drive the reaction or signal in the assay, not the substance you’re measuring. A calibrant (calibration standard) provides known reference values to convert the assay signal into a real concentration, but it isn’t the target of the measurement. For example, in a glucose test, glucose is the analyte, while the blood sample is the material tested, the reagents create the measurable response, and calibrants ensure the reading is accurate.