FTIR (Fourier Transform InfraRed) spectroscopy is the most popular analytical technology for industrial applications requiring the continuous measurement of multiple parameters simultaneously. Typically, FTIR analysers are employed for process control and emissions monitoring, however, due to the robustness and flexibility of this technique it can also be applied in a wide variety of different applications, which will be discussed in greater detail below.
FTIR gas analysers identify and measure gaseous compounds by their absorbance of infrared radiation. This is possible because every molecular structure has a unique combination of atoms, and therefore produces a unique spectrum when exposed to infrared light. Instrumental analysis of the spectrum (2 to 12 micrometer wavelength) enables the qualitative identification and quantitative analysis of the gaseous compounds in the sample gas.
Importantly, FTIR analysers are able to simultaneously measure multiple analytes in complex gas matrices, detecting virtually all gas-phase species (both organic and inorganic, except diatomic elements such as nitrogen, oxygen and noble gases like helium or neon). For example, the Gasmet™ FTIR gas analyser collects a complete infrared spectrum (a measurement of the infrared light absorbed by molecules inside the sample gas cell) 10 times per second. Multiple spectra are co-added together according to a selected measurement time (improving accuracy by raising the signal-to-noise ratio). The actual concentrations of gases are calculated from the resulting sample spectrum using a patented modified Classical Least Squares analysis algorithm.
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