Fourier transform infrared (FTIR) is a powerful gas measurement technology, that offers true multicomponent capability. This technology that was originally used for challenging research applications has since proved very reliable and versatile and has become the industry standard in many challenging emissions monitoring applications.
Most gases absorb infrared light at some wavelengths in the infrared spectrum. The position and intensity of the absorptions are determined by the molecular structure of the gas and this means that each gas will have a unique absorption pattern. This unique pattern can be used like a fingerprint to identify and measure each gas in the sample.
An FTIR analyzer works by simultaneously scanning the entire infrared spectrum and then calculating the concentrations of each gas in the sample based on their characteristic absorptions. The fact that the entire infrared spectrum is scanned at once means that all the gases in the sample can be measured simultaneously. This allows for very quick multicomponent measurements and for compensation for any cross-interference.
As all gases are measured by scanning the same infrared spectrum, adding new compounds can be done easily in the software without requiring any changes to the hardware. The recorded spectra are also unaltered by the analysis performed on them and can therefore always be re-analyzed at a later point. This allows for traceable data and facilitates for instance retrospectively checking the measurements for new gases.
All this makes FTIR the ideal solution for a variety of applications where multiple gases need to be measured quickly, accurately and reliably.