DETECTORS Photo Ionization Detector - PID Overview The Photo Ionization Detector (PID) responds to all molecules whose ionization potential is below 10.6eV, including aromatics and molecules with carbon double bonds. The PID is nondestructive, so the sample can be routed through the PID and on to other detectors. It is often used in series with the FID and / or DELCD. PID detection limits for aromatics are in the ppb range; purge and trap concentration Benzene of the sample can lower detection limits to the ppt range. Because of its selective sensitivity, use of the PID is mandated in several EPA methods. The PID detector consists of a 10.6 electron volt (eV) UV lamp mounted on a thermostatted, low-volume (100µL), flow-through cell. The temperature is adjustable from ambient to 250oC. Three detector gain levels (LOW, MEDIUM and HIGH) are provided for a wide range of sample concentrations. The PID lamp is held in place by a spring-loaded plate, so that the lamp may be quickly removed for cleaning and replaced without any special tools. The PID can run on air carrier for gasless operation, or for stream monitoring applications where the entire stream of sample is directed through the detector (no column is used). PID in series with a DELCD and an FID on an SRI 8610C chassis 100µL detector cell (the area in the center of the TeflonTM seal ring) Spring-loaded retaining plate High voltage band in black plastic hood over lamp anode ring Heater block BNC connector to amplifier Collector electrode support union Collector electrode Amplifier gain switch

DETECTORS Photo Ionization Detector - PID Theory of Operation 10.6eV PID Lamp (SRI Part # 8670-1242) Anode ring Cathode base The SRI PID design uses a 10.6eV lamp with a high voltage power supply. Sample laden carrier gas flows from the analytical column into the PID sample inlet, where it is streamed through a 100µL flow-through cell. When sample molecules flow into the cell, they are bombarded by the UV light beam. Molecules with an ionization potential lower than 10.6eV release an ion when struck by the ultraviolet photons. These ions are attracted to a collector electrode, then sent to the...

DETECTORS Photo Ionization Detector - PID file £dil tb cqui rii ion Help PID Noise Run Column: 15m MXT-VOL Carrier: Helium @ 10mL/min PID gain: LOW PID temp: 150oC PID current: 70 PID noise averages less than 50pV from peak to peak ■lOCO PID BTEX Analysis (in series with FID and DELCD) Sample: 1^L 100ppm BTEX plus Column: 15m MXT-VOL Carrier: Helium @ 10 mLs/min PID gain: LOW PID temp: 150oC PID current: 70 Results: Component Benzene TCE Toluene PCE Ethyl Benzene 6.700 Ortho Xylene 7.383 Bromoform 7.650 Total

DETECTORS Photo Ionization Detector - PID General Operating Procedure The capillary column enters the PID cell from inside the column oven through the bulkhead fitting in the insulated oven wall. The column may be installed with the lamp in place. Insert the capillary column into the PID detector inlet until the column stops at the lamp window inside the PID cell, then pull it back about 1mm from the lamp window. Tighten the 1/8” nut with the graphite ferrule at the PID inlet to secure the column in place. The collector electrode is positioned at the factory and should not touch the column under...

DETECTORS Photo Ionization Detector - PID Troubleshooting and Maintenance Cleaning the PID Lamp The PID lamp window Over time, during normal operation, a film of contaminants will condense on the PID lamp window. Typically, this film is a result of stationary phase column bleed. To minimize contaminant condensation and thus lamp window cleaning, avoid heating the column any higher than absolutely necessary. Contaminant condensation can block the photons, reducing lamp emissions and sensitivity. Therefore, the PID lamp window must be cleaned when an appreciable change in sensitivity has been observed...