spike 

https://doi.org/10.1351/goldbook.08047
Material with known quantity values added to an analytical sample.
Notes:
  1. The material can be a reference material or a certified reference material.
  2. The known quantity value is often a fraction or concentration.
  3. A spike may be used to estimate the recovered quantity value ratio or compensate for systematic measurement error.
  4. "Spike" used as a verb is the addition of a spike to a sample.
Source:
PAC, 2021, 93, 997. (Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)) on page 1017 [Terms] [Paper]
Citation: 'spike' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08047 RIS BibTex EndNote
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