EFFECT OF AMMONIA ON THE RESPONSE OF THE ELECTRON-CAPTURE DETECTOR (ECD)

The effect of ammonia on the electron capture detector (ECD) response has been investigated. Nitrogen with different ammonia concentrations (5-20%) was used as make-up gas. Compared to pure nitrogen, the ECD re sponse decreased when the ammonia concentration in the make-up gas was 5%, However, the response increased when the ammonia concentration wa s 20%. The response factor of 4-chlorophenol increased 4 fold when amm onia was 20%. Also, di- and tri-chlorophenols increased by 30-50%. The nitroaromatic compounds responses increased by about 23.7 times with 20% ammonia in the make-up gas. The signal-to-noise (S/N) increased wh en 20% ammonia in nitrogen was used as make-up gas compared to pure ni trogen. Also, the detector linearity increased by 50% with ammonia.