TECHNOLOGY
Electron Capture Detector
The instrument
Lovelock invented in 1957 —
exquisitely sensitive to trace gases — whose readings led to the discovery of CFCs in the atmosphere, the identification of pesticide residues in the environment, and ultimately the recognition of the ozone hole.
The electron capture detector (ECD) is a type of gas chromatography detector developed by James Lovelock in 1957 while working at the British National Institute for Medical Research. The device exploits the tendency of certain molecules — particularly those containing halogens — to capture free electrons, producing a detectable decrease in current. The ECD's extraordinary sensitivity — capable of detecting compounds at concentrations of parts per trillion — made it possible to measure atmospheric trace gases that had previously been below
the threshold of instrumental detection. Lovelock used his own device to measure chlorofluorocarbons (CFCs) in remote atmospheric samples in the early 1970s, finding them in locations and concentrations that established them as truly global pollutants. This data was essential to the work of Mario Molina and Sherwood Rowland, who in 1974 proposed that CFCs were destroying stratospheric ozone — the hypothesis that ultimately led to the
Montreal Protocol and the discovery of the Antarctic ozone