Photoionization detectors

The near-ir spectmm of ethylene oxide shows two peaks between 1600—1700 nm, which are characteristic of an epoxide. Near-ir analyzers have been used for verification of ethylene oxide ia railcars. Photoionization detectors are used for the deterrnination of ethylene oxide ia air (229—232). These analyzers are extremely sensitive (lower limits of detection are - 0.1 ppm) and can compute 8-h time-weighted averages (TWAg). 

A typical photoionization detector is shown in Figure 3.11. The UV source is a discharge lamp, containing an inert gas or gaal mixture at low pressure, that emits monochromatic light of 1... 

RELATIONSHIP BETWEEN PHOTOIONIZATION DETECTOR RESPONSE (10.2 eV) AND MOLECULAR STRUCTURE... 

W. Haag and C. Wrenn, Handbook of Theory and Applications of Direct-reading Photoionization Detectors (PIDs), RAE Systems Inc., Sunnyvale, CA (2002). 

The primary methods of analyzing for lead in environmental samples are AAS, GFAAS, ASV, ICP/AES, and XRFS (Lima et al. 1995). Less commonly employed techniques include ICP/MS, gas chromato-graphy/photoionization detector (GC/PID), IDMS, DPASV, electron probe X-ray microanalysis (EPXMA), and laser microprobe mass analysis (LAMMA). The use of ICP/MS will become more routine in the future because of the sensitivity and specificity of the technique. ICP/MS is generally 3 orders of magnitude more sensitive than ICP/AES (Al-Rashdan et al. 1991). Chromatography (GC,... 

An ultasensitive simultaneous multi-element method of determination for As, Se, Sb and Sn in aqueous solution, consists of hydride generation, collection in a cryogenic trap and end analysis by GC-PID (photoionization detector) LOD ca 1 ng Sn/L for a 28 mL sample. No drying or CO2 scrubbing is necessary before the cold trap35. 

D. C. Locke, B. S. Dhingra, and A. D. Baker. Liquid-Phase Photoionization Detector for Liquid Chromatography. Anal. Chem., 54(1982) 447-450. 

Photoionization Detector (PID) UV radiation ionizes column effluent 5 pg/s 7 Aromatics... 

A paper has been published showing the use of the photoionization detector [26], Polyaromatic hydrocarbons are very sensitive using the photoionization detector and the levels detected did not break any new ground in terms of sensitivity. It did inspire HNS Systems (Newtown MA, USA), who market a photoionization detector, to try the detector with a capillary system, interfaced to a Lee Scientific 602 supercritical fluid chromatography (Lee Scientific, Salt Lake City, Utah, USA). 

The photoionization detector is to a certain extent specific in that only compounds that can be ionized by a UV lamp will give a response. The solvents used were dichloromethane and acetonitrile, both of which should... 

The amount detected by this system (0.3pg on column) was below the level which could have been determined using a flame ionization detector. Initial indications show that the photoionization detector may be a very useful detector for people who wish to get to lower levels on the supercritical fluid chromatography and cannot concentrate their sample. 

Cutter et al. [121] have described a method for the simultaneous determination of arsenic and antimony species in sediments. This method uses selective hydride generation with gas chromatography using a photoionization detector. 

Lovelock in 1960, first introduced the photoionization detector but unfortunately its reported usages have been more or less scarce. 

Methods Samples were collected for the period of three consecutive days for indoors and outdoors, at each microenvironment. Sampling duration was for 8 h from 10 00 am to 6 00 pm during all the seasons. TVOC levels were measured using a portable data logging Ion Science PhoCheck+ photoionization detector (PID) equipped with 10.6eV ultra-violet lamp4. The sampling instrument was placed... 

One method (EPA 8020) that is suitable for volatile aromatic compounds is often referred to as benzene-toluene-ethylbenzene-xylene analysis, although the method includes other volatile aromatics. The method is similar to most volatile organic gas chromatographic methods. Sample preparation and introduction is typically by purge-and-trap analysis (EPA 5030). Some oxygenates, such as methyl-f-butyl ether (MTBE), are also detected by a photoionization detector, as well as olefins, branched alkanes, and cycloalkanes. 

Certain false positives are common (EPA 8020). For example, trimethylben-zenes and gasoline constituents are freqnently identified as chlorobenzenes (EPA 602, EPA 8020) becanse these componnds elnte with nearly the same retention times from nonpolar columns. Cyclohexane is often mistaken for benzene (EPA 8015/8020) becanse both compounds are detected by a 10.2-eV photoionization detector and have nearly the same elntion time from a nonpolar colnmn (EPA 8015). The two compounds have very different retention times on a more polar column (EPA 8020), but a more polar column skews the carbon ranges (EPA 8015). False positives for oxygenates in gasoline are common, especially in highly contaminated samples. 

It is possible that the photoionization detector (1) may not be completely selective for aromatics and can lead to an overestimate of the more mobile and toxic aromatic content and (2) the results from the two analyses, purge-able and extractable hydrocarbons, can overlap in carbon number and cannot simply be added together to get a total concentration of the total petroleum hydrocarbons. 

MS = mass spectroscopy PID = photoionization detector ppbv = parts per billion by volume... 

Photoionization detector (h) High energy electrons (Beta particles)... 

Organolead Compounds. Methods for sampling and analysis of tetraethyl lead and tetramethyl lead were developed based on collection on XAD-2, desorption with pentane, and analysis by gas chromatography with a photoionization detector. 

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