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PID - SRI Instruments
PID - Photo Ionization Detector
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Responds to molecules with carbon double
bonds and aromatics
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Sensitive (down to 10 ppb) and non-destructive
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Mandated in several EPA methods
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Extremely long lamp life
The SRI PID uses the industry standard 10.6eV PID lamp in a spring-
loaded mount, which allows the lamp to be removed, cleaned and re-
installed in seconds, without tools.
Use of the Photo Ionization Detector is mandated in several EPA methods (8021, TO-14, etc.) because of its sensitivity
and selectivity. Detection limits for aromatics are in the low picogram (ppb) range. Because it is non-destructive, it is often
run in series with other detectors
typically the
or multiple chromatograms from a
single injection.
The PID is also able to run on air carrier, which can be useful in situations where no gas is available, or for stream
monitoring applications where no column is used to separate compounds.
Unlike other PID designs, the lamp on the SRI PID can be easily removed, without tools, for the periodic cleaning of the
lamp window to avoid interference from column bleed build-up. Lamps can last years on the SRI PID because only the
lamp window is heated, not the entire body of the lamp.
Our PID consists of an insudtry standard UV lamp mounted on a thermostatted, low-volume, flow-through cell.
The temperature is adjustable from ambient to 250°C. The 10.6 electron volt UV lamp emits energy at a wavelength of
120 nanometers, which is sufficient to ionize most aromatics (benzene, toluene, xylene, etc.) and many other
molecules (H
2
S, hexane, ethanol) whose ionization potential is below 10.6eV. Methanol and water, for example,
have ionization potentials greater than 10.6eV and do not respond on the PID.
This PID chromatogram shows a