Why must stock mucicarmine solution be used in a fume hood?

• A. Because it releases hydrogen chloride vapors when exposed to atmospheric moisture
• B. Because it stains best in bright light
• C. Because it is highly volatile and explosive
• D. Because it reacts with aldehydes in the air

Answer: (A)

Handling stock mucicarmine involves an acidic reagent that releases hydrogen chloride gas when it comes into contact with moisture in the air. Because HCl fumes are highly corrosive and irritating to the eyes, skin, and lungs, using a fume hood provides containment and proper ventilation to protect the user from inhalation and exposure. The other ideas (that it stains best in bright light, that it’s highly volatile/explosive, or that it reacts with aldehydes in the air) aren’t the safety concern here; the risk is the release of corrosive HCl vapors in the presence of moisture.