Inorganic gases detection

Phthalocyanines were chosen for these experiments because they are electronic semiconductors and because they are quite stable materials — an important consideration in fabricating any practical gas-detecting device. A considerable body of literature exists describing the physical and chemical properties of the phthalocyanines. A review of the work prior to 1965 is contained in the chapter by A. B. P. Lever in Volume 7 of Advances in Inorganic Chemistry and Radiochemistry (2). Electrical properties of phthalocyanines have been receiving increased attention in recent years. The photoconductivity of metal-free phthalocyanine has been studied in detail (3,4). Electrical properties of lead phthalocyanine have been studied extensively, especially by Japanese workers (5, ,7,8i). They have also studied the alteration of the conductivity of this material upon exposure to oxygen ( ,10.). The effects of a series of adsorbed gases (0, , CO, and NO) on the conductivity of iron phthalo-... 

Detection for inorganic gas analysis has been almost entirely carried out by means of thermal conductivity since ionisation detector response is minimal. 

Quantitative determination of the various organic and inorganic components detected by the qualitative tests. Most often, ion chromatography is used for determination of sulfate phosphate and polyphosphates chelates such as NTA, EDTA, and gluconate and other lower molecular weight components. Capillary electrophoresis may also be used. Gas chromatography is applied to quantification of solvents and propellants. Specialized tests are required to determine poly aery late builders One quick semi-quantitative test is based on pyrolysis GC-MS of a water extract after addition of tetramethylammonium hydroxide. Peaks of methyl acrylate and methyl fumarate indicate the presence of acrylate and maleate polymers and/or copolymers (14). 

Odanake et al. [1] have reported the application of gas chromatography with multiple ion detection after hydride generation with sodium borohydride to the determination of mono and dimethyl arsenic compounds, trimethyl arsenic oxide and inorganic arsenic in soil and sediments. Recoveries in spiking experiments were 100-102% (mono and dimethyl arsenic compounds and inorganic arsenic) and 72% (trimethyl arsenic oxide). 

Chau et al. [f6] described a hexane extraction procedure to extract tetramethyllead, trimethylethyllead, methyltriethyllead, dimethyldiethyllead and tetraethyllead from marine sediments. The extracted compounds were analysed in their authentic forms by a gas chromatographic-atomic absorption spectrometric system. Other forms of organic and inorganic lead do not interfere. The detection limit was O.Ofmg kg-1 as lead. 

The ion formation may occur in the bulk solution before the electrospray process takes place or in the gas phase by protonation or salt adduct formation, or by an electrochemical redox reaction. Polar compounds already exist in solution as ions therefore, the task of the electrospray is to separate them from their counterions. This is the case of many inorganic and organic species and all those compounds that show acidic or basic properties. Proteins, peptides, nucleotides, and many other bio- and pharmaceutical analytes are typical examples of substances that can be detected as proto-nated or deprotonated species. 

Grosjean, D Liquid Chromatography Analysis of Chloride and Nitrate with Negative Ultraviolet Detection Ambient Levels and Relative Abundance of Gas-Phase Inorganic and Organic Acids in Southern California, Environ. Sci. Technol, 24, 77-81 (1990). 

Male Fischer 344 rats were exposed by inhalation to 1% 2-chloro-1,1,1 -trifluoroethane for 2 h and then urine was collected for 24 h. Urinary metabolites identified by 19F nuclear magnetic resonance and gas chromatography/mass spectrometry were 2,2,2-trifluoroethyl glucuronide (16%), trifluoroacetic acid (14%), trifluoroacetaldehyde hydrate (26%), trifluoroacetaldehyde-urea adduct (40%) and inorganic fluoride (3%). A minor, unidentified metabolite was also detected. No covalent binding of fluorine-containing metabolites was observed in the liver and kidney from the exposed rats (Yin et al., 1995). In-vitro incubation of 2-chloro-1,1,1-trifluoroethane with rat liver microsomes and an NADPH-generating system has been shown to involve a dechlorination reaction (Salmon et al., 1981) that produced trifluoroacetaldehyde hydrate as the only metabolite (Yin et al., 1995). 

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