UCSF Lab Standard Operating Procedure
Chemical Process, Name or Hazard Class:
Methyl Mercaptan
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☒Hazardous Chemical
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Purpose
Methyl Mercaptan: is a colorless gas with a smell like rotten cabbage and a weak acid. It is a natural
substance found in the blood and brain of humans and other animals as well as plant tissues. It is also one of
the main chemicals responsible for bad breath and the smell of flatus.
It is mainly used to produce methionine, which is used as a dietary component in poultry and animal feed.[2] It
is also used in the plastics industry and as a precursor in the manufacture of pesticides. It is released as a byproduct of wood pulping in pulp mills. It is also used as a gas odorant in natural gas, LPG, and propane.
Synonyms: Methanethiol, Methyl Mercaptan (DOT), Mercaptomethane, Thiomethanol, and Methyl sulfhydrate.
Physical & Chemical Properties/Definition of Chemical Group
CAS#: 74-93-1
Class: Flammable gas, Target Organ Effect, Highly toxic by inhalation
Molecular Formula: CH4S
Form (physical state): Liquefied gas
Color: colorless
Methyl Mercaptan
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Modified from SOP templates developed by UCLA EH&S (http://www.sop.ehs.ucla.edu/)
Boiling point: 6°C (43°F) – lit.
Potential Hazards/Toxicity
Flash Point: -18°C (0°F) – closed cup
Methyl Mercaptan mixes with air to form explosive mixtures. The gas is heavier than air and may travel along
the ground; distant ignition possible. The substance decomposes on burning producing toxic fumes including
sulfur oxides and hydrogen sulfide . Reacts violently with strong oxidants. Reacts with water , steam or acids
to form flammable and toxic gas. It ships as a USDOT Zone C Poison Inhalation Hazard (UN1064).
Acute toxicity
Oral LD50
Inhalation LC50
LC50 Inhalation - mouse - 2 h - 6.5 mg/m3
Dermal LD50
no data available
Other information on acute toxicity
no data available
Target Organs
Nerves., Blood, Liver
Potential health effects
Inhalation May be fatal if inhaled. May cause respiratory tract irritation.
Ingestion May be harmful if swallowed.
Skin May be harmful if absorbed through skin. May cause skin irritation.
Eyes May cause eye irritation.
Signs and Symptoms of Exposure
Absorption into the body leads to the formation of methemoglobin which in sufficient concentration causes
cyanosis. Onset may be delayed 2 to 4 hours or longer., Cyanosis, anemia, Nausea, Headache, Vomiting,
Dizziness, Weakness,Incoordination., Tremors, Unconsciousness.
Engineering Controls
Handle using under a certified chemical fume hood (certified once every year by EH&S) with good ventilation
or glove box and electrically grounded lines and equipment.
Personal Protective Equipment (PPE)
Respirator Protection
If lab personnel would like to use respirator on a voluntary basis, they must be trained and fit-tested by
EH&S. This is a regulatory requirement. (http://or.ucsf.edu/ehs/8193-DSY/version/default/part/4/data/)
Hand Protection
Gloves must be worn, such as neoprene or nitrile gloves. Use proper glove removal technique to avoid any
skin contact. Insulated PVC/Butyl gloves preferred to prevent potential of frostbite from the liquefied gas.
NOTE: Consult with your preferred glove manufacturer to ensure that the gloves you plan on using are
compatible with Methyl mercaptan.
Refer to glove selection chart from the links below:
Methyl Mercaptan
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Modified from SOP templates developed by UCLA EH&S (http://www.sop.ehs.ucla.edu/)
http://www.ansellpro.com/download/Ansell_8thEditionChemicalResistanceGuide.pdf
OR
http://www.allsafetyproducts.biz/page/74172
OR
http://www.showabestglove.com/site/default.aspx
OR
http://www.mapaglove.com/
Eye Protection
Face shield and safety glasses Use equipment for eye protection tested and approved under appropriate
government standards such as NIOSH (US) or EN 166(EU).
Skin and Body Protection
Flame resistant/cotton lab coats must be worn and be appropriately sized for the individual and buttoned to
their full length. Laboratory coat sleeves must be of sufficient length to prevent skin exposure while wearing
gloves. Full length pants and close-toed shoes must be worn at all times by all individuals that are occupying
the laboratory area. The area of skin between the shoe and ankle should not be exposed.
Hygiene Measures
Wash thoroughly and immediately after handling. Remove any contaminated clothing and wash before reuse.
First Aid Procedures
If inhaled
Move into the fresh air immediately and give oxygen. If not breathing give artificial respiration. Seek medical
attention immediately.
In case of skin contact
Immediately flush skin with plenty of water for at least 15 minutes. If contact with liquid form, treat like
frostbite and do not remove any clothing. Seek medical attention immediately. Wash any contaminated
clothing before reuse. Thoroughly clean shoes before reuse.
In case of eye contact
Rinse thoroughly with plenty of water for at 15 minutes. If possible, check for and remove any contact lenses
and consult a physician.
If swallowed
Do NOT induce vomiting unless directed by medical personnel. Never give anything by mouth to an
unconscious person. Seek medical attention immediately.
Special Handling and Storage Requirements
Precautions for safe handling: Avoid contact with skin and eyes and inhalation. Do not breathe gas. Avoid of
vapors, mist, or gas. Use only with adequate ventilation or respiratory protection. Keep sparks, flames, and
other sources of ignition away, as well as extreme temperature and direct sunlight.
Materials to avoid:
Strong oxidizing agents, Strong bases, Strong oxidizing agents, Reacts violently with water.
Conditions for safe storage: Keep container tightly closed in a cool, dry, and well-ventilated fire-proof place
away from incompatible materials and conditions. Stench. Store in original container.
Methyl Mercaptan
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Modified from SOP templates developed by UCLA EH&S (http://www.sop.ehs.ucla.edu/)
Spill and Accident Procedure
Chemical Spill Dial 9-911 from campus phone or 415-476-1414 from cell phone or 415-2068522 (SFGH only)
Spill – Assess the extent of danger. Assist contaminated or injured persons. Evacuate the spill area.
Avoid breathing vapors. If possible, confine the spill to a small area using a spill kit or absorbent
material. Keep others from entering contaminated area (e.g., use caution tape, barriers, etc.).
Small (<1 L) – If you have training, you may assist in the clean-up effort. Use appropriate personal
protective equipment and clean-up material for chemical spilled. Double bag spill waste in clear
plastic bags, label and take to the next chemical waste pick-up.
Large (>1 L) – Dial 9-911 from campus phone or 415-476-1414 from cell phone or 415-2068522 (SFGH only) for assistance.
Chemical Spill on Body or Clothes – Remove clothing and rinse body thoroughly in emergency
shower for at least 15 minutes. If discomfort persists, proceed to the Emergency Department. If no
further discomfort is experienced, have the SDS ready and contact Poison Control Hotline at 1-800222-1222 for further exposure information. Notify your direct supervisor and EH&S at 415-4761300 during work hours, or 9-911 during non-working hours and weekends.
Chemical Splash Into Eyes – Immediately rinse eyeball and inner surface of eyelid with water for
15 minutes by forcibly holding the eye open. If discomfort persists, proceed to the Emergency
Department. If no further discomfort is experienced, have the SDS ready and contact Poison
Control Hotline at 1-800-222-1222 for further exposure information. Notify your direct
supervisor and EH&S at 415-476-1300 during work hours, or 9-911 during non-working
hours and weekends.
Medical Emergency Dial 9-911 (campus phone) or 476-6911 (cell phone)
Note: All serious injuries must be reported to EH&S at 415-476-1300 within 8 hours.
Non-Life Threatening Emergency– Go to Occupational Health Programs (OHP) Clinic, 415-8857580, 2330 Post Street, Suite 460 Hours of Operation for Appointments: Monday - Friday
7:30 a.m. - 4:00 p.m. (except Holidays).
Note: All serious injuries must be reported to EH&S at 415-476-1300 within 8 hours.
Needle stick/puncture exposure (as applicable to chemical handling procedure) – Wash the
affected area with antiseptic soap and warm water for 15 minutes. For mucous membrane
exposure, flush the affected area for 15 minutes using an eyewash station. Page the needle stick
nurse by dialing 415-353-7842 (STIC).
Decontamination/Waste Disposal Procedure
Methyl Mercaptan
4
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Modified from SOP templates developed by UCLA EH&S (http://www.sop.ehs.ucla.edu/)
Clean contaminated surfaces with soap and water and paper towels. Dispose of the paper towels as
hazardous waste.
Safety Data Sheet (SDS) Location
Online SDS can be accessed at http://or.ucsf.edu/ehs/7241-DSY/msds.html
Protocol/Procedure
Quantities covered by this SOP:
______ (g , ml) to _______ (g, ml)
Temperature range covered by this SOP:
__ °C – __ °C
General Overview and Purpose:
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Procedure:
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NOTE
Any deviation from this SOP requires approval from the Principal Investigator.
Methyl Mercaptan
5
Date: Click here to enter a date.
Modified from SOP templates developed by UCLA EH&S (http://www.sop.ehs.ucla.edu/)