Method and system for generating interference spectra for low detection limits using reactor

A gas analysis system, comprising:

• a spectrometer for analyzing gas;
• a switched reaction device for switching between providing a sample stream to the spectrometer and providing a reacted sample stream to the spectrometer, the switched reaction device including an input line, an output line, a first path, and a second path, the input line positioned downstream of the sample stream, the output line positioned downstream of the input line and upstream of the spectrometer, the first path coupling the input line to the output line through a reactor, and the second path coupling the input line to the output line, wherein the second path avoids the reactor, wherein the output line is in fluid communication with the spectrometer;
• and
• a controller using the reacted sample stream to create spectra for analyzing the sample stream.