Term: electron capture detector
https://doi.org/10.1351/goldbook.E01981

Definition:
A small radioactive source containing 3H or 63Ni ionizes the molecules of the carrier gas (nitrogen or argon–methane), and a potential difference creates a small current. This current is reduced when an electronegative substance (such as a halocarbon) is introduced. The reduction in current is a measure of the concentration of the electronegative substance. The detection limit (threshold) varies greatly according to the substances to be analysed and can reach a mixing ratio of 10E-12. The linear dynamic range may be 10E4 but the maximum measuring value generally lies below 1 ppmv.

Related Terms:
1) radioactive source (http://doi.org/10.1351/goldbook.R05088).
2) carrier gas (http://doi.org/10.1351/goldbook.C00863).
3) detection limit (http://doi.org/10.1351/goldbook.D01628).

Source: PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2191 (https://doi.org/10.1351/pac199062112167)

Citation: 'electron capture detector' 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.E01981

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