Calibrants

Calibrants are substances or devices with well‑characterized physical or chemical properties that are used as reference standards to ensure the accuracy, precision, and traceability of analytical measurements. By providing a known response under defined conditions, calibrants allow instruments and methods to be calibrated, validated, and compared across laboratories.

In spectroscopy, mass spectrometry, and chromatography, calibrants typically consist of pure compounds with certified purity and known spectral, mass‑to‑charge, or retention characteristics. For example, a series of n‑alkanes may serve as retention time calibrants in gas chromatography, while a mixture of peptides with defined mass values is used to calibrate mass spectrometers. In nuclear magnetic resonance, reference compounds such as tetramethylsilane provide a fixed chemical shift scale.

Calibration procedures involve measuring the response of the calibrant, plotting it against the known quantity (e.g., concentration, mass, wavelength), and generating a calibration curve. The resulting function is applied to unknown samples to convert raw detector signals into meaningful analytical results. Routine verification with quality‑control calibrants detects drift, non‑linearity, or contamination.

Standards organizations, including the International Organization for Standardization (ISO), the National Institute of Standards and Technology (NIST), and the International Union of Pure and Applied Chemistry (IUPAC), define protocols for the selection, preparation, and certification of calibrants. Certified reference materials (CRMs) are a subset of calibrants that carry official documentation of their property values, uncertainty, and traceability to the International System of Units (SI).

Calibrants are essential in fields such as clinical chemistry, environmental monitoring, pharmaceutical analysis, and materials science, where reliable quantitative data underpin regulatory compliance, scientific research, and quality assurance. Proper use and documentation of calibrants ensure reproducibility and confidence in analytical results.