Automated measurement, atmospheric trace

Dasgupta Automated Measurement of Atmospheric Trace Gases... 

Bertman, S. B., Buhr, M. P., and Roberts, J. M., Automated cryogenic trapping technique for capillary GC analysis of atmospheric trace compounds requiring no expendable cryogens application to the measurement of organic nitrates, Anal. Chem., 65, 2944-2946, 1993. 

For such absorption measurements infrared lasers can be used which coincide with vibrational-rotational transitions of the investigated molecules (CO2 laser, CO laser, HF or DF lasers, etc.). Particularly useful are tunable infrared lasers (diode lasers, color-center lasers, or optical parametric oscillators, Vol. 1, Sect. 5.7), which may be tuned to selected transitions. The usefulness of diode lasers has been demonstrated by many examples [1451]. For instance, with a recently-developed automated diode laser spectrometer, which is tuned by computer control through the spectral intervals of interest, up to five atmospheric trace gases can be monitored in unattended operation. Sensitivities down to 50 ppt for NO2 and 300 ppt for NO have been reported [1371]. 

Dasgupta, P.K. (2002) Automated diffusion-based collection and measurement of atmospheric trace gases, in Sampling and Sample Preparation for... 

Komazaki, Y. Hamada, Y. Hashimoto, S. Fujita, T. Tanaka, S. Development of an automated, simultaneous and continuous measurement system by using a diffusion scrubber coupled to ion chromatography for monitoring trace acidic and basic gases (HCl, HNO3, SO2 and NH3) in the atmosphere. Analyst 1999,124 (8), 1151-1157. 

Instruments that can identity and quantify trace levels of VOCs have many potentially important applications beyond atmospheric science. For example, VOC emissions from foods and drinks are critical in our perception of their taste and smell. Food manufacturers are keen to understand the factors that contribute to flavour perception, and correlating VOC measurements with human trials of sensory perception is an important way of doing this. VOC emissions from foods and drinks can also be an indicator of quality. In particular, the onset of serious degradation may be characterized by the excessive emission of one or more VOCs, and these marker compounds therefore offer the key to an automated indication of food and drink decay. This is an area of investigation that is still very much in its infancy, but which may have very considerable implications for the food and drinks industries. 

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