Exposure, osmium tetroxide

Concentrations in air as low as IO7 g/ms can cause lung congestion, skin damage, or eye damage. Exposure to osmium tetroxide should not exceed 0.0016 mg/ms (8-hour time weighted average - 40-hour work week). 

A colourless solution of osmium tetroxide in hexane or dichloromethane upon exposure to benzene turns yellow instantaneously (Wallis and Kochi,... 

Lesion in bovine dentin with tubules protruding from degraded intertubular matrix (left degraded matrix right intact matrix). Demineralization in 0.1 M acetic acid pH 4.0, with subsequent exposure to bacterial collagenase. Fixed and demineralized with glutar-dialdehyde-acetic acid, post-fixed with osmium tetroxide ultrathin sections stained with uranyl acetate - lead citrate. 

Osmium tetroxide is poisonous by all routes of exposure. The vapor is an... 

Properties. Osmium tetroxide forms pale yellow crystals with a very characteristic odour (a possible description is that of a mixture of ozone and damp hay). It has a considerable vapour pressure at room temperature and so must be kept in stoppered container or (preferably) in sealed ampoules. The vapour is toxic (TLV 2.5 p.p.m.).558a The long-term occupational exposure limit (OEL) is 0.002mgm 3. 558b... 

Osmium and compounds Osmium tetroxide is a colorless to pale yellow crystalline solid with an odor that has been described as pungent or chlo-rine-like. Students and workers must take precautions in the use of osmium tetroxide. Prolonged periods of inhalation exposure to osmium tetroxide cause insomnia, digestive disturbance, and distress to the pharynx and larynx. ... 

American Conference of Governmental Industrial Hygienists (ACGIH). 1998. Osmium tetroxide. In TLVs and other occupational exposure values—1998. Cincinnati, OH ACGIH. 

Osmium tetroxide-mediated cis hydroxylation of a silyl enol ether has been demonstrated to produce the corresponding a-hydroxy ketone in moderate yield after exposure to an acidic woric-up, e.g. (64) to... 

The osmylation of arenes (Ar) with osmium tetroxide is a particularly informative system with which to illustrate the close interrelationship between the thermal and photochemical activation of electron-transfer oxidation. For example, a colorless solution of osmium tetroxide in n-hexane or dichlorometbane upon exposure to benzene turns yellow instantaneously. With durene an orange coloration develops and a clear bright red solution results from hexamethylbenzene. The quantitative effects of the dramatic color changes are illustrated in Figure 3 by the spectral shifts of the electronic absorption bands that accompany the variations in aromatic conjugation and substituents. The progressive bathochromic shift parallels the decrease in the arene ionization potentials (/F) in the order benzene 9.23 eV naphthalene... 

The morphology of ruber modified epoxy photopolymers was found to depend on the cure conditions as well as the nature and concentration of rubber. The commercially available acrylonitrile-butadiene copolymer rubber modifiers with varying percentages of acrylonitrile content were used. They were polymerized using a photocationic initiator involving a UV exposure followed by a thermal cure. Transmission electron micrographs of osmium tetroxide stained specimens, coupled with dynamic mechanical measurements indicated that phase separation and particle size distribution depended not only on rubber concentration and compatibility, but also on the cure conditions. 

For standard electron microscopy, cells and tissue are postfixed in 1% osmium tetroxide for 30 min to stain the membranes. Exposure to osmium tetroxide decreases the size of the silver particles and some might even disappear (Burry et al., 1992). Reducing both the concentration of osmium to 0.1% and processing for 10 min will prevent this loss of silver particles. 

A, Ultrastructure prior to ligh( exposure ( ). Glutaraldehyde plus osmium tetroxide... 

Figure 3.32. Electron micrograph of ultrathin section of irradiated ABS plastic (osmium tetroxide staining). Note cracking, which occurred after 400 h exposure to Fade-o-Meter irradiation. (Hirai, 1970.)...

The acute toxicity of osmium tetroxide is high, and it is a severe irritant of the eyes and respiratory tract. Exposure to osmium tetroxide vapor can damage the cornea of the eye. 

Chronic exposure to osmium tetroxide can result in an accumulation of osmium compounds in the liver and kidney and damage to these organs. Osmium tetroxide has been reported to cause reproductive toxicity in animals this substance has not been shown to be carcinogenic or to show reproductive or developmental toxicity in humans. 

Because of its high acute toxicity, osmium tetroxide should be handled in the laboratory using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, all work with osmium tetroxide should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Osmium tetroxide as solid or solutions should be stored in tightly sealed containers, and these should be placed in secondary containers. 

Incident 7.2.3.1 involved potential exposure to osmium tetroxide (OSO4). OsOa is hazardous due to its high toxicity and the fact that it easily sublimes at room temperature and pressure. It has little or no warning properties since you can t smeU it at concentrations that can seriously harm you. (See also Chemical Connection 7.1.4.1 If I Can Smell It, Am I in Danger )... 

University of Delaware, Office of Campus and Public Safety, Environmental Health and Safety. Exposure to Osmium Tetroxide available at http //www.udel.edu/ehs/osmiumtetroxide.html (accessed October 23, 2009). 

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