Photoionisation Detector (PID)
Definition
An electronic instrument that uses a UV lamp (typically 10.6 eV) to ionise organic vapour molecules and measures the resulting ion current. Detects aromatic and aliphatic hydrocarbons at ppb to ppm concentrations.
- Detection principle
- UV lamp ionises vapour molecules, ion current measured
- Lamp energy
- Typically 10.6 eV
- Sensitivity range
- Parts per billion to parts per million
- Target compounds
- Aromatic and aliphatic hydrocarbons
Common questions
How does a PID differ from a canine in accelerant screening?+
A PID gives a numeric, instrument-based reading that can be logged and repeated, while a canine gives a trained behavioural alert. Investigators often use the canine to narrow the search area quickly, then confirm and document specific spots with the PID before sampling.
Can a PID identify which accelerant is present?+
No. A PID only signals that ionisable vapour is present above background level, it does not distinguish gasoline from other hydrocarbon sources. Confirmation and identification require laboratory analysis of a collected sample, typically by gas chromatography.
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