【求助】为什么六通阀切换后会出现一较大倒峰？？

As is the case with all detectors for gas chromatography, thermal control of
a FID is an important requirement. The block enclosing the detector should be
heated above the temperature of the column to avoid the condensation of sample
components in the transfer lines and jet. In addition, the temperature must be
above 100 oC to prevent water condensation. Since the temperature of the body
of the detector has a slight effect on the detection mechanism it must be stable.
However, it is more important to keep the detector from getting too hot since
solid surfaces heated by the flame can emit electrons (i.e., thermionic ionization).
For example, a large sample or component that can increase the temperature can
cause a positive detector response, including samples or components that otherwise
would have given a negligible response (e.g., CO). Under such conditions,
water may give a negative peak, as it decreases the temperature of the flame.Overheating the detector can also lead to electrical leakage across insulators,
causing instability in the detector output current.
《Modern Practice of Gas Chromatography》