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Type of SOP: ☐ Process ☒ Hazardous Chemical ☐ Hazardous Class
Purpose
Tetramethylammonium hydroxide (TMAH) is a corrosive and highly toxic chemical. If not stored and handled properly, this can pose a serious threat to the health and safety of laboratory personnel, emergency responders and chemical waste handlers. Hence, it is important to follow safety protocols to handle this chemical.
Uses: Tetramethylammonium hydroxide (TMAH or TMAOH) is a quaternary ammonium salt with the molecular formula (CH
3
)
4
NOH. It is used as an anisotropic etchant of silicon. It is also used as a basic solvent in the development of acidic photoresist in the photolithography process. Since it is a phase transfer catalyst, it is highly effective in stripping photoresist. It is also used as a surfactant in the synthesis of ferrofluid, to prevent agglomeration.
Synonyms: Tetramethylammonium hydroxide 20% in methanol; TMAH 25%; Methanaminium; Ammonium
Tetramethyl Hydroxide.
Physical & Chemical Properties/Definition of Chemical Group
CAS#: 75-59-2
Class: Poison.
Molecular Formula: (CH
3
)
4
NOH
Tetramethylammonium Hydroxide (TMAH)
1
Modified from SOP templates developed by UCLA EH&S ( http://www.sop.ehs.ucla.edu/ )
Date: Click here to enter a date.

Form (physical state): Liquid
Color: Colorless or straw-colored
Boiling point: 60-65° C
Potential Hazards/Toxicity
Hazards Associated with Various Routes of Exposure:
Inhalation:
Extremely destructive to tissues of the mucous membranes and upper respiratory tract. May produce upper airway edema, respiratory failure, pulmonary edema and pnemonitis. Symptoms may include burning, wheezing, laryngitis, shortness of breath. Toxic effects from the Methanol component are exerted upon nervous system, particularly the optic nerve. Once absorbed into the body, it is very slowly eliminated.
Symptoms of overexposure may include headache, drowsiness, nausea, vomiting, blurred vision, blindness, coma, and death. A person may get better but then worse again up to 30 hours later.
Ingestion:
Corrosive. Swallowing can cause severe burns of the mouth, throat, and stomach. Can cause sore throat, vomiting and diarrhea. Methanol component is Toxic. Symptoms parallel inhalation. Can intoxicate and cause blindness.
Skin Contact:
Corrosive. Symptoms of redness, pain, and severe burn can occur. Methanol component is a defatting agent and may cause skin to become dry and cracked. Skin absorption can occur; symptoms may parallel inhalation exposure.
Eye Contact:
Corrosive. Contact can cause blurred vision, redness, pain and severe tissue burns.
Chronic Exposure:
Marked impairment of vision has been reported. Repeated or prolonged exposure may cause skin irritation.
Aggravation of Pre-existing Conditions:
Persons with pre-existing skin disorders or eye problems or impaired liver or kidney function may be more susceptible to the effects of the substance.
Engineering Controls
Tetramethylammonium hydroxide (TMAH) must be handled under a chemical fume hood that has been inspected and certified by EH&S within the last one year.
Personal Protective Equipment (PPE)
Respiratory Protection
Tetramethylammonium Hydroxide (TMAH)
2
Modified from SOP templates developed by UCLA EH&S ( http://www.sop.ehs.ucla.edu/ )
Date: Click here to enter a date.

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
Disposable nitrile gloves may only provide brief protection and must be replaced if they become wetted. More protective gloves are the Stansolv or Tri-Ionic glove models sold by MAPA. Tri-Ionic clean room gloves provide excellent protection from TMAH exposure.
NOTE: Consult with your preferred glove manufacturer to ensure that the gloves you plan on using are compatible with Tetramethylammonium hydroxide (TMAH).
Refer to glove selection chart from the links below: 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
Wear safety goggles (not glasses).
Skin and Body Protection
Wear a buttoned lab coat, full length pants, and closed-toe shoes.
Hygiene Measures
Avoid contact with skin, eyes and clothing. Wash hands before breaks and immediately after handling the product.
First Aid Procedures
If inhaled
Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.
In case of skin contact
Immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Get medical attention immediately. Wash clothing before reuse. Thoroughly clean shoes before reuse.
In case of eye contact
Immediately flush eyes with plenty of water for at least 15 minutes, lifting lower and upper eyelids occasionally. Get medical attention immediately.
If swallowed
If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Never give anything by mouth to an unconscious person. Get medical attention immediately.
Special Handling and Storage Requirements
Tetramethylammonium Hydroxide (TMAH)
3
Modified from SOP templates developed by UCLA EH&S ( http://www.sop.ehs.ucla.edu/ )
Date: Click here to enter a date.

Stability: Stable under ordinary conditions of use and storage. Readily absorbs CO2 from the air.
Hazardous Decomposition Products: Carbon oxides, nitrogen oxides and formaldehyde gas form when heated to decomposition.
Incompatibilities: Strong acids and oxidizing agents; attacks many plastics and rubber. May react with metallic aluminum and generate hydrogen gas.
Conditions to Avoid: Heat, flames, ignition sources and incompatibles.
NOTE: You should NOT handle TMAH containing materials when working alone. Have lab buddy system in place.
Spill and Accident Procedure
Chemical Spill Dial 9-911 from campus phone or 415-476-1414 from cell phone or 415-206-
8522 (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 415-206-
8522 (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 1-800-
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.
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.
Tetramethylammonium Hydroxide (TMAH)
4
Modified from SOP templates developed by UCLA EH&S ( http://www.sop.ehs.ucla.edu/ )
Date: Click here to enter a date.

Non-Life Threatening Emergency– Go to Occupational Health Programs (OHP) Clinic, 415-885-
7580, 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
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.
Tetramethylammonium Hydroxide (TMAH)
5
Modified from SOP templates developed by UCLA EH&S ( http://www.sop.ehs.ucla.edu/ )
Date: Click here to enter a date.