Osmium tetraoxide, with a molecular weight of 254.2 g/mol, is a crucial component in fixation for electron microscopy within the life science field. This compound, identified by its CAS Number 20816-12-0, requires stringent handling due to its acute oral toxicity as indicated by the GHS signal word "Danger." Safety precautions such as wearing protective gear, including safety goggles and gloves, are essential when working with this substance. It is important to note that osmium tetraoxide should not be ingested, smoked around, or handled by unauthorized individuals. The compound has a Melting Point of 105°F and a Boiling Point of 266°F at 760 mmHg. Its relative Vapour Density compared to air is 8.8.

• CAS Number: 20816-12-0
• Molecular Formula: O4Os
• Molecular Weight: 254.2
• Exact Mass: 255.94114
• Boiling Point: 266 °F at 760 mmHg (NIOSH, 2024)
• Melting Point: 105 °F (NIOSH, 2024)
• Density: Relative Vapour Density (air = 1): 8.8
• GHS Signal Word: Danger
• Hazard Statements:
• H300: Fatal if swallowed [Danger Acute toxicity, oral]
• H301: Toxic if swallowed [Danger Acute toxicity, oral]