Hydrogen Cyanide and Cyanide Salts

HYDROGEN CYANIDE AND CYANIDE SALTS

STANDARD OPERATING PROCEDURE TEMPLATE

Type of SOP: ProcessHazardous ChemicalHazard Class

HAZARD OVERVIEW

Extremely Toxic!

Hydrogen cyanide and its salts are extremely toxic. Exposure to as little as 50-150 mg can cause immediate collapse and death.

Hydrogen cyanide is a gas, and as such inhalation is a prominent route of exposure. Great care must be taken to absolutely avoid inhalation of HCN gas. All other routes of exposure are also fatal. Notably, aqueous solutions of HCN are readily absorbed through the skin and eyes, and absorption of as little as 50 mg can be fatal.

Cyanide salts, such as sodium and potassium cyanide, are solids. However, they convert quickly to gaseous HCN when exposed to acid or moisture. Therefore, as in the case of HCN, great care must be taken to absolutely avoid inhalation of any vapors, as well as any aerosolized dust.

Initial symptoms of cyanide exposure include weakness, headache, dizziness, rapid breathing, nausea and vomiting. If these symptoms are observed while in an area where cyanide is being handles, get medical attention immediately by dialing 9-911 from a campus phone.

Hydrogen cyanide is an extremely flammable gas, and must be stored and handled away from ignition sources. Cyanide salts are generally noncombustible solids. However, reaction with acid and moisture releases flammable hydrogen cyanide.

EXPOSURE LIMITS

Cal-OSHA has established maximum inhalation exposure limits for workers in occupational settings for over 500 chemicals. These are known as Permissible Exposure Limits and can not legally be exceeded. For hydrogen cyandide the PEL is very low:

4.7 ppm – unlike most PELs which are time-weighted (8 hrs. generally) average exposures, this is a “ceiling” PEL which should never be exceeded

Therefore, work with hydrogen cyanide should always be done in a fume hood, glove box, or in totally-sealed containers to keep inhalation exposures as low as possible. Contact EH&S if you believe you are being exposed. In some instances EH&S can do quantitative exposure monitoring. Because hydrogen cyanide is also a serious skin contact hazard, skin exposure should also be absolutely minimized.

PERSONAL PROTECTIVE EQUIPMENT (PPE)

See the PPE information under Sec. II of the UCSB Chemical Hygiene Plan regarding:

the UC PPE Policy and policy summary (what PPE is needed and when/where to use)
obtaining your PPE via use of the Laboratory Hazard Assessment Tool
glove selection criteria
respirator use, etc.

Viton or Butyl rubber gloves should be worn when handling hydrogen cyanide. Nitrile gloves are adequate for cyanide salts. Splash goggles should be used in all cases

ENGINEERING/VENTILATION CONTROLS

For further information see the following pages in Sec. II of the Chemical Hygiene Plan:

Fume Hood Usage Guide
Criteria for Implementing Engineering Controls

SPECIAL HANDLING PROCEDURES AND STORAGE REQUIREMENTS

Handling

Great care must be taken to avoid all exposure to hydrogen cyanide and cyanide salts, most notably inhalation and skin contact. The proper use of engineering/ventilation controls and skin and eye protection is imperative to avoid a high risk of fatality. .

Maintain awareness of the pH of any cyanide salt solutions, as an acidic pH will release the very toxic and flammable hydrogen cyanide gas.

Storage

Hydrogen cyanide containers should be protected from physical damage and stored in a ventilated area away from ignition sources and other materials. It should not be stored for extended periods (>90 days) due to explosion risk as a result of decomposition.

Cyanide salts should be stored in a cool, dry location, separated from acids.

SPILL AND INCIDENT PROCEDURES

See directions under the “Chemical Incident” tab of the UCSB Emergency Information Flipchart – should already be posted in all labs.

DECONTAMINATION

Using proper personal protective equipment as outlined above, decontaminate equipment and bench tops using soap and water and properly dispose of all chemical and contaminated disposables as hazardous waste following the guidelines below.

WASTE DISPOSAL

See “Chemical Waste Disposal” in Sec. II of the UCSB Chemical Hygiene Plan.

Keep a separate and dedicated waste container for cyanide waste. Maintain awareness of the pH of the accumulated waste, as an acidic pH will release the very toxic and flammable hydrogen cyanide gas.

PRIOR APPROVAL/REVIEW REQUIRED

As they deem necessary, the PI/supervisor should insert here any prior approval or review needed before an individual can do the operation

DESIGNATED AREA

As they deem necessary, the PI/supervisor should insert here any information about whether a special use-area is designated for this material/process

SAFETY DATA SHEETS

Found online at:

LAB-SPECIFIC PROTOCOL (required)

Add appropriate lab-specific information here describing how this material(s) is generally used. E.g., name of protocol, frequency done, scale, temperature, etc.