Due to the high sensitivity of the Electron Capture Detector (ECD) in gas chromatographs—especially its sensitivity to substances with high electronegativity, such as elements like F, Cl, and O—it is highly susceptible to contamination.
The forms of contamination include:
① Loss of the radioactive source;
② Contamination on the electrode surface or the radioactive source;
③ Contamination in the gas path.
When the gas chromatograph is contaminated, it will exhibit phenomena such as high background noise, baseline drift, negative responses, and severe peak tailing.
The main factors leading to detector contamination are:
(1) Impure carrier gas containing impurities such as H₂O and O₂;
(2) Contamination of the silica gel pad at the injection port;
(3) Loss, decomposition, or other issues of the stationary phase or stationary liquid in the chromatographic column;
(4) Contamination at the column head;
(5) Presence of certain sensitive substances or high-boiling-point substances in the sample or solvent.