Sensitizers sulfur dioxide

Phosphoms(V) sulfide is a mild skin irritant and may cause dermatitis in sensitive individuals. The primary health ha2ard results from the Hberation of hydrogen sulfide after contact with moisture. Contact with moisture also forms phosphoric acid. A secondary ha2ard is the formation of sulfur dioxide when phosphoms(V) sulfide bums. The oral LD q of in rats is 389 mg/kg the OSHA standard time-weighted average (TWA) is 1 mg /m (33). 

Ammonium sulfate [7783-20-2], (NH 2 U4, is a white, soluble, crystalline salt having a formula wt of 132.14. The crystals have a rhombic stmcture d is 1.769. An important factor in the crystallization of ammonium sulfate is the sensitivity of its crystal habit and size to the presence of other components in the crystallizing solution. If heated in a closed system ammonium sulfate melts at 513 2° C (14) if heated in an open system, the salt begins to decompose at 100°C, giving ammonia and ammonium bisulfate [7803-63-6], NH HSO, which melts at 146.9°C. Above 300°C, decomposition becomes more extensive giving sulfur dioxide, sulfur trioxide, water, and nitrogen, in addition to ammonia. 

Elemental sulfur in either its ore or its refined state can generaUy be recognized by its characteristic yeUow color or by the generation of sulfur dioxide when it is burned in air. Its presence in an elemental state or in a compound can be detected by heating the material with sodium carbonate and mbbing the fused product on a wet piece of silver metal. A black discoloration of the silver indicates the presence of sulfur. The test is quite sensitive. Several other methods for detecting smaU amounts of elemental sulfur have also been developed (34). 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

A variety of models have been developed to study acid deposition. Sulfuric acid is formed relatively slowly in the atmosphere, so its concentrations are beUeved to be more uniform than o2one, especially in and around cities. Also, the impacts are viewed as more regional in nature. This allows an even coarser hori2ontal resolution, on the order of 80 to 100 km, to be used in acid deposition models. Atmospheric models of acid deposition have been used to determine where reductions in sulfur dioxide emissions would be most effective. Many of the ecosystems that are most sensitive to damage from acid deposition are located in the northeastern United States and southeastern Canada. Early acid deposition models helped to estabUsh that sulfuric acid and its precursors are transported over long distances, eg, from the Ohio River Valley to New England (86—88). Models have also been used to show that sulfuric acid deposition is nearly linear in response to changing levels of emissions of sulfur dioxide (89). 

Sulfur dioxide Bleached spots, bleached areas between veins, chlorosis insect injury, winter and drought conditions may cause similar markings Middle-aged leaves most sensitive oldest least sensitive Mesophyll cells 0.3 785 8 hr... 

The sulfur dioxide analyzer based on the ultraviolet principle is a sensitive instrument. Its detection limit can be less than one ppbv (parts per billion by volume). When used in emission measurements, the sample gas IS normally diluted prior to the measurement using a diluting stack sampler. 

Thermal Conductivity Detector In the thermal conductivity detector (TCD), the temperature of a hot filament changes when the analyte dilutes the carrier gas. With a constant flow of helium carrier gas, the filament temperature will remain constant, but as compounds with different thermal conductivities elute, the different gas compositions cause heat to be conducted away from the filament at different rates, which in turn causes a change in the filament temperature and electrical resistance. The TCD is truly a universal detector and can detect water, air, hydrogen, carbon monoxide, nitrogen, sulfur dioxide, and many other compounds. For most organic molecules, the sensitivity of the TCD detector is low compared to that of the FID, but for the compounds for which the FID produces little or no signal, the TCD detector is a good alternative. 

Sulfones are known to undergo elimination of sulfur dioxide upon photolysis/64 Thus sulfone (33) yields hydrocarbon (34) in the presence of a photosensitizer (A > 320 nm) or with light of A < 280 nm in the absence of sensitizer ... 

The chemistry involved in this explosively unstable system is reviewed [1]. The mechanism of the trigger reactions that initiate the exothermic decomposition of chlorate-sulfur mixtures has been studied. Mixtures containing 1-30% of sulfur can decompose well below the m.p. of sulfur, and addition of sulfur dioxide, the suspected chemical trigger, causes immediate onset of the reaction [2], Autoignition of stoichiometric mixtures can be as low as 115°C, with frictional sensitivity at 5N, the lowest load the test apparatus permitted. Both were dependent upon the history of the sulphur used [3],... 

Mixtures of potassium and solid carbon dioxide are shock-sensitive and explode violently on impact, and carbon monoxide readily reacts to form explosive carbonylpotassium (potassium benzenehexoxide) [1]. Dichlorine oxide explodes on contact with potassium [2], Potassium ignites in dinitrogen tetraoxide or dinitrogen pentaoxide at ambient temperature and incandesces when warmed with nitrogen oxide or phosphorus(V) oxide [3], At — 50°C, potassium and carbon monoxide react to give dicarbonylpotassium, which explodes in contact with air or water, or at 100°C. At 150°C, the product is a trimer of this, potassium benzenehexoxide. The just-molten metal ignites in sulfur dioxide [4],... 

Also, a CL reaction between sulfur dioxide and oxygen atoms was studied by Mulcahy and Williams [124] and proposed for the analysis of sulfur dioxide with a sensitivity of 0.001 ppm. However, a disadvantage of this analysis lies in the difficulty for finding a stable source of oxygen atoms. 

Sulfite, sulfur dioxide Ce(IV)-3-(cyclohexylamino)propanesulfonic acid (sensitizer), air 0.02 Xg/mL 2... 

Matsumura, Y., et al., The effects of ozone, nitrogen dioxide, and sulfur dioxide on experimentally induced allergic respiratory disorder in guinea pigs. IV. Effects on respiratory sensitivity to inhaled acetylcholine, Am. Rev. Respir. Dis. 105, 2, 262, 1972. 

Kohno, Y., Matsumura, H., Kobayashi, T. (1998). Differential sensitivity of 16 tree species to simulated acid rain or sulfur dioxide in combination with ozone. In Bashkin, V. N., Park,... 

Another class of "chain scission" positive resists is the poly(olefin sulfones). These polymers are alternating copolymers of an olefin and sulfur dioxide. The relatively weak C-S bond is readily cleaved upon irradiation and several sensitive resists have been developed based on this chemistry (49,50). One of these materials, poly(butene-l sulfone) (PBS) has been made commercially available for mask making. PBS exhibits an e-beam sensitivity of 1.6 pC cm-2 at 20 kV and 0.25 pm resolution. 

An important application of P.Gr.8 is in the coloration of rubber. The pigment, however, is not suitable for use in blends which contain large amounts of basic fillers. It is somewhat sensitive to cold vulcanization. The colored articles usually perform well in general application but are not entirely fast to aromatic hydrocarbons and to some fats, and they are sensitive to acid and sulfur dioxide. P.Gr.8 also colors some plastics, especially LDPE and polystyrene. Heat stable up to 220°C, P.Gr.8 grades equal step 2-3 on the Blue Scale for lightfastness. Other areas of application include wallpaper and artists colors. 

Data on aerosol formation from irradiated automobile exhaust 5.193.23. 239 confirm the marked sensitivity to hydrocarbon type observed in individual hydrocarbon studies. Aerosol formation increases with the olefinic and aromatic fuel content. However, changes in mode of engine operation (acceleration, idle) and inorganic variables (sulfur dioxide, relative humidity) have a more pronounced effect on aerosol formation than change in fuel composition. ... 

Johnston, H. S., and K. Dev Jain. Sulfur dioxide sensitized photochemical oxidation of hydrocarbons. Science 131 1523-1524, 1960. 

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