Phosgene detectors

For a quantitative determination in large-scale chemical processing, automatic gas level sensors, such as the OLDHAM-GZ-ARRAS (France) M/42, having a four-channel programmable alarm system, are used [19]. Electrochemical phosgene detectors (0.1-3.0 ppm) and handy pumps with phosgene tubes (AUER GAS-TESTER II) (from 0.1 ppm) are also employed. 

Elemental composition C 12.14%, 0 16.17%, Cl 71.69%. Phosgene can be analyzed by GC using FID or a balogen-specific detector or by GC/MS. Ambient air may be collected in a metal container placed in an argon bath or condensed into any other type cryogenically cooled trap. Alternatively, the air may be collected in a Tedlar bag. The sampled air may be sucked by a condensation mechanism into tbe GC column. 

Air drawn through a midget impinger containing 10 mL of 2% aniline in toluene (by volume) phosgene reacts with aniline forming carbanilide (1,3-dipheny-lurea) solvent evaporated at 60°C under N2 flow residue dissolved in 1 mL acetonitrile carbanilide analyzed by reverse-phase HPLC with an UV detector set at 254 nm (EPA Method T06) recommended flow rate 200 mL/min sample volume 20 L. 

To rely upon the detection of phosgene by its odour would, therefore, be hygienically undesirable. Fortunately, safe and reliable methods for its detection are available and, in particular, the extent of exposure is conveniently provided [145] by special detector badges... 

Gas chromatography (g.c.) has proven to be particularly useful for the analysis of phosgene in a wide range of concentrations. A katharometer (thermal conductivity) detector is most frequently employed for routine use (down to about 200 p.p.m. [1339]), but very low concentrations in air, in the p.p.b. [563,598,1039,1663,1887] or even sub-p.p.b. range [448,1886] have been analysed using an electron capture detector [98a,1253,2025]. For such... 

A piezoelectric crystal coated with methyltrioctylphosphonium dimethylphosphate has been recently described as a good detector for phosgene in air [1976], The sensitivity of this device is in the range of 1-35 p.p.m. 

Clearly, the preferred method to use for the analysis of phosgene depends upon the particular application to hand. For routine use in the laboratory, for monitoring the ambient air, impregnated paper strips and Dra ger tubes can be recommended as both reliable and easy to use. On the plant, automatic methods for continuous analysis would be appropriate, and one of the electrical or automated spectroscopic techniques would be suitable. For accurate measurement of very low (p.p.b.) concentrations however, a gas chromatographic procedure using one of the special detectors is most suitable. 

As with phosgene (see Section 3.2.5.1), gas chromatography is a particularly useful technique for the determination of a broad range of concentrations of carbonyl difluoride. The thermal conductivity detector is the only detection system reported to be used for this compound. The detector response for the thermal conductivity detector is shown to be linear over a wide range of COF concentrations [559]. 

Figure 22.4 Separation of racemic propranolol as oxazolidone derivative with a dinitrobenzoylphenylglycine phase [reproduced with permission from I.W. Wainer, T.D. Doyle, K.H. Donn and J.R. Powell, J. Chromatogr., 306, 405 (1984)]. Conditions sample, whole-blood extract, 2.5 h after administration of an 80 mg dose of propranolol racemate, derivatized to oxazolidone with phosgene column, 25 cm X 4.6 mm i.d. stationary phase, 3,5-DNB-phenylglycine, 5 [xm mobile phase, hexane-isopropanol-acetonitrile (97 3 1), 2mlmin fluorescence detector, 290-335 nm IS, internal standard (oxazolidone derivative of pronethalol).

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... 

C. The characteristic signs and symptoms of phosgene oxime exposure may suggest its presence. There are no automatic detectors available for use in the field. 

The M18 detection kit and the M256A1 kit are mihtary items. The M18 is a colorimetric device for measuring the concentration of selected airborne chemicals. The Ml8 comes with detector tubes for cyanide, phosgene. Lewisite, sulfur mustard, and nerve agents GA, GB, GD, and VX. 

Hazardous materials or "Hazmat" teams are routinely equipped with a variety of chemical detectors and monitoring kits, primarily employing chemical-specific tests indicating only the presence or absence of a suspected chemical or class of chemical. The most common detectors test for pesticides, chlorine, and cyanide, but not specifically for phosgene, vesicants, or nerve agents. Although chemical tests, detectors, and monitors used by the military are commercially available for civilian use, they have not been acquired by civilian organizations in appreciable numbers. 

Suleiman A, GuUbault GG (1984b) A coated piezoelectric crystal detector for phosgene. Anal Chim Acta 162 97-102 Tadigadapa S, Mated K (2009) Piezoelectric MEMS sensors state-of-the-art and perspectives. Meas Sci Technol 20 092001-092030... 

Personnel wearing masks can detect phosgene leaks with ammonia vapor devices, as phosgene produces white fumes in the presence of ammonia. Other detection devices such as detector tubes and specialized leak detection instruments may also be used. 

This instrument is a handheld, portable CWA monitoring detector that uses IMS. The CAM-2 has the added detection algorithm for identifying hydrogen cyanide, phosgene, and chlorine, in addition to conventional CWAs. 

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