Ambient Air Quality Monitoring and Analysis Technologies

When combined, certain gases produce high energy chemical reactions that emit light energy (photons), known as chemiluminescence.  Specifically, light emission results when electronically excited molecules decay to lower energy states. These emissions are detected by photomultiplier tubes and, by measuring the intensity and characteristics of the light emitted, the presence and concentration of various gases can be accurately determined.  Our analyzers that operate using this principle employ advanced optical technology for high sensitivity and reliable readings.  Explore them here:

Gas chromatography (GC) is a proven analytical tool that was initially developed in the 1950s and is now a widely applied technique for separating and analyzing compounds that can be vaporized without decomposition.  Because GC is best used to measure volatile compounds and utilizes gas columns that are stable and long lasting, GC is ideal for certain gas measurement applications.  Explore instruments that use GC here.

Gas scrubbing technology combines filtration, catalytic conversion, and oxidation to produce pollutant free air (Zero Air) from ambient air.  Zero Air is then used for instrument calibration and as diluent air supply for spanning ambient air analyzers.  Gas scrubbing technology removes NO, NO₂, O₃, SO₂, CO, and hydrocarbons. Our gas scrubbing technology passes pressurized air into a column of Purafil (potassium permanganate on alumina) which oxidizes NO to NO₂. From there the air passes through a column of activated charcoal which removes NO₂, SO₂, O₃ and hydrocarbons. Lastly, the air is moved into the reactor where it is heated to 350°C over a catalytic surface which converts CO to CO₂ and any remaining hydrocarbons, including methane, to water and CO₂. This process results in a pollutant free stream of air.

The relative simplicity of NDIR technology provides precise, long-term gas analysis while lowering operating cost throughout the life cycle of the instrument. NDIR analyzers operate on the principle that gases absorb radiation in specific infrared wavelength ranges. As infrared light passes through a container of gas, a non-dispersive infrared sensor detects how much of the filtered light wavelength the gas absorbs. A measurement of gas concentrations is obtained. Thermo Scientific analyzers combine this technology with advanced optical filters to enable even more precise measurements.

Optically Enhanced Fourier Transform Infrared (OE-FTIR) using breakthrough StarBoost Technology enables commercial FTIR gas analysis that dramatically increases sensitivity, linearity and dynamic range over narrow spectral bands of interest. It utilizes specialized optics, electronics and analysis algorithms to go beyond traditional FTIR gas analysis capabilities.

This enhancement technology, proven in demanding applications such as ethylene oxide and formaldehyde measurement, enables users to achieve single-digit ppb detection limits for many applications. It can be supplied as a turnkey add-on to the MAX-iR Gas Analyzer and is compliant with several regulatory methods including US Environmental Protection Agency (EPA) method 320 and American Society for Testing and Materials (ASTM) D6348.  

Our Pulsed Fluorescence analyzers operate on the principle that H₂S can be converted to SO₂. As the SO₂ molecules absorb ultraviolet (UV) light and become excited at one wavelength, the molecules then decay to a lower energy state emitting UV light at a different wavelength. The pulsing of the UV source lamp serves to increase the optical intensity and a greater UV energy throughput and lower detectable SO₂ concentrations are realized.

Because this technology uses reflective bandpass filters, which are less subject to photochemical degradation and are more selective in wavelength isolation than transmission filters, increased detection specificity and long-term stability are achieved.

UV photometric gas analyzers take advantage of the fact that certain gases exhibit a pronounced absorption band in the spectral range of 200nm to 400nm. Because of the high absorption behavior of the gases in specific bands, analyzers that use UV photometry can reliably detect very low concentrations of target gases.  Additionally, results using this method are resistant to interference from the presence of water vapor and carbon dioxide. This technology is also advantageous in that additional optical spectrometers or filter elements are not required.