|Use:||Photo ionization detectors (PIDs) are used to detect aromatic hydrocarbons (a PID can detect most VOCs with a carbon range of 6 (such as benzene) to 10 (such as naphthalene)).|
The PID is comprised of an ultraviolet lamp that emits photons (a quantum unit of light energy) which are absorbed by the analyte in an ionization chamber. Ions (atoms or molecules that have gained or lost electrons and thus have a net positive or negative charge) produced during this process are collected by electrodes. The current generated provides a measure of the analyte concentration.
PIDs are commonly used as detectors in portable gas chromatographs (which separate the specific analyte types). Because only a small fraction of the analyte molecules are actually ionized, this method is considered nondestructive allowing it to be used in conjunction with another detector to confirm analysis results. This is easily accomplished by connecting the exhaust port of the PID to a flame-ionization detector (FID) or electron capture detector. In addition, PIDs are available in portable hand-held models.
1. Non-Halogenated VOCs
3. Some Halogenated VOCs
|Requires extraction to liquid or gas phase||Requires extraction to liquid or gas phase||BETTER|
|Selectivity:||Technique measures the contaminant indirectly.|
|Susceptibility to Interference:||High.|
|Detection Limits :||10-100 ppm (soil); 0.5-10 ppm (water).|
|Turnaround Time per Sample:||Minutes.|
ASTM Standards/EPA Methods:
No applicable ASTM standards or EPA methods are cited for this technology.
|Previous Page||Sample Access/Collection Matrix||Sample Analysis Matrix||Home||Areas of Interest||Next Page|