IR Breath Analyser
Definition
Infrared absorption at about 3.4 micrometres (C-H stretch) or 9.5 micrometres (C-O stretch). Specific and quantitative; used in Intoxilyzer 8000 and evidential stationary instruments.
- Wavelengths used
- About 3.4 micrometres (C-H) or 9.5 micrometres (C-O)
- Detection basis
- Infrared absorption, specific and quantitative
- Example instruments
- Intoxilyzer 8000 and other evidential stationary units
- Setting
- Fixed evidential-grade instruments, not handheld screeners
Common questions
Why is IR absorption considered more specific than fuel-cell breath testing?+
The C-H and C-O absorption bands correspond to the functional groups in ethanol specifically, so the instrument responds much less to other volatile compounds a subject might have in their breath, reducing the risk of a false elevated reading from interferents.
Why are IR breath analysers deployed as stationary station instruments rather than roadside handhelds?+
The optical bench and calibration required for evidential accuracy make these units bulkier and more sensitive to handling than a fuel-cell screening device, so they are used to confirm results in a controlled setting after an initial roadside screen.
Related terms
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- Fuel-Cell Breath Analyser
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- Wet-Bath Simulator
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- Widmark Formula
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