The following is a listing of carrier and support gas impurity effects on the operation of specific gas chromatographic detectors. Trace impurities increase background signal and baseline noise while reducing usable discharge current, resulting in impaired sensitivity. Oxygen contamination modifies detector response and increases noise.
Hydrocarbons can quench signal response and generate ghost peaks.
Hydrocarbon contamination must be at a minimum in the carrier gas to prevent ghost peaks and baseline drift, and to reduce background noise. Hydrocarbons in air and fuel gases cause increased noise and background current. Hydrocarbon and carbon dioxide contamination causes signal quenching and increased background noise. Impurities can become concentrated on purge and trap sampling devices and injected into the device. Atmospheric, neon, and hydrogen impurities cause baseline noise, signal polarity shifts, reduced sensitivity, and instability.