Detection, Identification, and Monitoring
Keep three verbs distinct. Detect means an alarm or indicator says something is present. Identify means the specific agent or isotope is named. Monitor means tracking change over time or space with a defined purpose, such as establishing a perimeter or clearing a site.
Chemical
Field tools include colorimetric papers and tickets, which are presumptive and class-level only. They tell you nerve or blister activity, not which agent. Handheld detectors using ion mobility, Raman, or infrared spectroscopy give faster specificity but are subject to library limits, interferents, and false alarms. Colorimetric tubes quantify a known vapor. Treat every field result as provisional until confirmed by a laboratory method or a second orthogonal technology.
Biological
Immunoassays and PCR-based platforms provide rapid, presumptive results; culture remains the reference standard and takes days. Environmental sampling requires a sampling plan, documented chain of custody, and background or negative controls.
Radiological
Three instrument types do different jobs and are frequently confused in questions. A dose-rate meter measures exposure per unit time at a point. A contamination meter (survey instrument) finds material on surfaces and people, and the probe choice matters: alpha particles are stopped by clothing, skin, and even a sheet of paper, so alpha surveys need a thin-window probe held close and slow. Gamma spectroscopy identifies which isotope is present. Personal dosimeters record cumulative dose, not dose rate.
Worked example
A meter reads 100 mR/h at the perimeter. A responder stands there for 30 minutes: cumulative dose is about 50 mR. Same reading, different question.
Rule of thumb
Detect fast, identify slow, confirm always, and never commit resources on one unverified reading.