Detection process
Detection process
This domain tests how odor is sampled, measured, and interpreted. You must choose a method that fits the question: real-time safety, regulatory compliance, source diagnosis, or community complaint investigation.
Core rules
- Sensory methods use human panels or field olfactometers; instrumental methods use sensors, colorimetric tubes, sorbent tubes with GC-MS, or continuous monitors.
- Dynamic olfactometry dilutes a sample to the detection threshold and reports odor concentration in odor units (ouE/m3). Field olfactometry uses a portable device at the site.
- Sampling must avoid adsorption and contamination: use appropriate bags or canisters, minimize hold time, and follow temperature and humidity limits.
- Calibrate instruments and include blanks and duplicates. Panel selection and training affect sensory results.
Worked example
A fence-line complaint needs a defensible odor measurement. Use a field olfactometer or collect a Tedlar bag sample for dynamic olfactometry; record wind, temperature, and time. A portable electrochemical H2S meter is useful for worker safety and source tracking, but it will not measure mercaptans or volatile fatty acids. For an unknown industrial VOC, use a sorbent tube and GC-MS.
Traps
- Using a colorimetric tube outside its range or after expiry.
- Storing H2S samples in bags too long; H2S can adsorb or react.
- Reporting a single meter reading as total odor.
- Ignoring panel variability and detection versus recognition thresholds.