Title: electron capture detector
Long Title: IUPAC Gold Book - electron capture detector
DOI: 10.1351/goldbook.E01981
Status: current

Definition
A small radioactive source containing $\ce{^{3}H}$ or $\ce{^{63}Ni}$ 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 \(10^{-12}\). The linear dynamic range may be \(10^{4}\) but the maximum measuring value generally lies below \(1\ \rm{ppmv}\).

Related Terms
- carrier gas: https://goldbook.iupac.org//terms/view/C00863
- detection limit: https://goldbook.iupac.org//terms/view/D01628
- radioactive source: https://goldbook.iupac.org//terms/view/R05088

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

Other Outputs
- html: https://goldbook.iupac.org/terms/view/E01981/html
- json: https://goldbook.iupac.org/terms/view/E01981/json
- xml: https://goldbook.iupac.org/terms/view/E01981/xml

Citation: 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. 10.1351/goldbook.E01981
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
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Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-06-20T02:12:02+00:00