Photo-ionization Detector

The contractor at Site H had established area and personnel sampling consistent with HAZWOPER requirements. A photo ionization detector (PID) and a real-time aerosol monitor (RAM) were used on a daily basis to screen for potentially hazardous levels of contaminants. On a weekly basis, personal air samples were collected and submitted for laboratory analysis. PPE requirements, however, were often not based on this data because the oversight agency had established inflexible minimum PPE requirements. The audit team found many of the PPE requirements on Site H to be excessive in light of site monitoring data and hazard determinations. 

Polycyclic Aromatic Hydrocarbon Physiologically Based Pharmacodynamic Physiologically Based Pharmacokinetic polychromatic erythrocytes permissible exposure limit photo ionization detector picogram picomole... 

Additional detectors currently available use other technologies such as electrochemical detectors for blister, nerve, blood, and choking agents, and infrared spectroscopy detectors or photo ionization detectors for the detection of blister and nerve... 

ECO = electron capture detector ED = electrochemical detector FID st flame ionization detector GC = gas chromatography HECD = Hall s electrolytic conductivity detector HPLC = high performance liquid chromatography MEC = molecular emission cavity analysis MS - mass spectrometry HD = photo-ionization detector... 

As a minimum, the flame ionization detector (FID) or the photo-ionization detector (PID) must be available at industrial sites handling hazardous substances. 

A photo-ionization detector (PID) measures VOCs in concentrations from ppbv up to lOOOOppmv. A PID is a very sensitive broad-spectrum monitor, like a low-level lower flammable limit (LEL) monitor. 

The use of more sensitive and selective, or even specific, detectors This approach is exemplified by the introduction of the photo-ionization detector (used in gas chromatography, [GC]), which is more sensitive and more selective than the flame-ionization detector hitherto commonly used in GC. 

The photo ionization detector (PID) contains an ultraviolet lamp that emits photons that are absorbed by compounds (aromatic rings, alkynes, and alkenes) in the ionization chamber. The ions created are then collected at electrodes, thus giving a signal. The most common use for this detector is for the analysis of BTEX. 

Sulfur adsorption experiments were carried out in a flow reactor at 773 K and l atm using a gaseous mixture containing 50 ppm of H2S in H2. The evolution of H2S was measured by frontal analysis with a photo-ionization detector. The total amount of adsorbed sulfur (St) was determined when the sample was saturated by H2S and a constant concentration of H2S in the exit gas was observed. Then, the sample was treated with pure H2 and the amount of reversibly held sulfur (Sr) was determined. The amount of irreversibly held sulfur (S-) was calculated as the difference between St and Sr. 

A frontal analysis with a photo-ionization detector allowed the amoimt of sulfur adsorbed by the catalyst (Stot) to be measured. After the catalyst was saturated with sulfur, pure hydrogen was passed through the sample for 10 h, which led to the desorption of some sulftir (Srev). The difference between Stot and S v allows the determination of the amount of irreversible sulfur adsorbed at 500°C. 

Other than phosgene and the cyanide agents, most chemical warfare agents are thought to have ionization potentials of less than 10.6 eV. Therefore screening with photo ionization detectors (PIDs) and flame ionization detectors (FIDs) is possible. However, because these systems will not differentiate... 

Figure 2.16 Electron capture detector(ECD) (a) and photo-ionization detector (PID) (b). The BCD must be installed in an well ventilated position owing to it containing a radioactive source. The PID contains a UV source from which the photons are emitted, having a pre-selected energy, using a filter which prevents undesired carrier gas ionization M + hv M+ - - e ). Examples of filters LiF at ll.SeV, MgFj at 9.6-10 eV, sapphire at 8.4 eV. On contact with the electrodes the molecules return to uncharged state, ionization being therefore reversible. The use of the make-up gas provides an optimal flow.

The primary method of analyzing carbon disulfide in air is by adsorption on an activated charcoal tube followed by solvent elution for subsequent quantification. GC equipped with either an electron capture detector (ECD), photo-ionization detector (PID), or FPD has been used for measuring carbon disulfide after elution from the solid phase. Detection limits of low ppm levels of carbon disulfide in the air sample were achieved with these techniques (McCammon et al. 1975 Peltonen 1989 Smith and Krause 1978 UK/HSE 1983). NIOSH has recommended GC/FPD (method 1600) for determining carbon disulfide in air. The range of quantification is 3-64 ppm for a 5-L air sample (NIOSH 1984b). 

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