Metabolomics studies the small-molecule metabolites present in a biological sample, commonly using mass spectrometry or nuclear magnetic resonance. A measurement can compare metabolic states, but different analytical methods detect different portions of the chemical mixture.
A peak intensity is not automatically an absolute concentration: extraction efficiency, ionization, matrix effects, and instrument drift can alter the signal. Standards, blanks, and pooled quality-control samples help distinguish biological variation from analytical variation.
A pooled quality-control sample combines representative portions of study samples and is measured repeatedly to monitor analytical consistency. In metabolomics, it provides a shared mixture against which changes in retention, signal intensity, or instrument drift can be tracked.
It is distinct from a biological replicate and from a certified concentration standard. A stable pooled sample supports assessment of measurement reproducibility, but does not by itself prove correct identification or absolute quantification of every metabolite.
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