Standard Operating Procedure
Tetramethylammonium hydroxide (TMAH)
(Methanol solutions)
This is an SOP template and is not complete until: 1) lab specific information is entered into the
box below 2) lab specific protocol/procedure is added to the protocol/procedure section and
3) SOP has been signed and dated by the PI and relevant lab personnel.
Print a copy and insert into your
Laboratory Safety Manual and Chemical Hygiene Plan.
Refer to instructions for assistance.
Department:
Chemistry
Date SOP was written:
1/14/2013
Date SOP was approved by PI/lab supervisor:
Principal Investigator:
Richmond Sarpong
Internal Lab Safety Coordinator/Lab Manager:
Lab Phone:
1/14/2013
Rebecca Murphy
510-643-2485
Office Phone:
510-643-6312
Emergency Contact:
Richmond Sarpong 626-644-2407
Location(s) covered by this SOP:
Latimer 834, 836, 837, 838, 839, 842, 844, 847, 849,
907
(Name and Phone Number)
(Building/Room Number)
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 (CH3)4NOH. 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.
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Synonyms: Tetramethylammonium hydroxide (up to 25%) in methanol; TMAH; Ammonium Tetramethyl
Hydroxide.
Physical & Chemical Properties/Definition of Chemical Group
CAS#: 75-59-2
Class: Acutely toxic chemical. Poison. Corrosive.
Molecular Formula: (CH3)4NOH
Form (physical state): Liquid
Color: Colorless or straw-colored
Boiling point:
60-65° C (in methanol)
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 pneumonitis. 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.
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Personal Protective Equipment (PPE)
Respiratory Protection
If the exposure limit is exceeded and engineering controls are not feasible, wear a supplied air, fullfacepiece respirator, air line hood, or full-facepiece self-contained breathing apparatus. Breathing air
quality must meet the requirements of the CalOSHA respiratory protection standard (8 CCR 5144).
Respirators should be used only under any of the following circumstances:
 As a last line of defense (i.e., after engineering and administrative controls have been
exhausted).
 When Permissible Exposure Limit (PEL) has exceeded or when there is a possibility that PEL will
be exceeded.
 Regulations require the use of a respirator.
 An employer requires the use of a respirator.
 There is potential for harmful exposure due to an atmospheric contaminant (in the absence of
PEL)
 As PPE in the event of a chemical spill clean-up process
Lab personnel intending to use/wear a respirator mask must be trained and fit-tested by EH&S. This is a
regulatory requirement.
Hand Protection
Disposable nitrile gloves only provide brief protection and must be replaced if they become wetted. If
more extensive contact is expected use more protective gloves such as the Stansolv A-10 gloves sold by
MAPA (11 mil nitrile).
NOTE: Consult with your preferred glove manufacturer to ensure that the gloves you plan on using are
compatible with tetramethylammonium hydroxide (TMAH) solution in methanol.
NOTE: Lab-specific information on glove selection may be included in the Protocol/Procedure section.
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
Long pants, closed-toed and closed-heeled shoes, cotton-based clothing/attire, and flame resistant lab
coat must be worn for protecting against chemical hazards.
Hygiene Measures
Avoid contact with skin, eyes and clothing. Wash hands before breaks and immediately after handling the
product.
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Engineering Controls
NOTE: Lab-specific information on engineering controls may be included in the Protocol/Procedure
section.
Tetramethylammonium hydroxide (TMAH) should be handled under a chemical fume hood.
First Aid Procedures
Notify supervisor and EH&S immediately. Follow up with a call to 510-642-9090 to report the incident.
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
NOTE: Lab-specific information on handling and storage may be included in the Protocol/Procedure
section.
Storage
Do not store together with acids. Store away from oxidizing agents. Store under inert gas if possible.
Store in cool, dry conditions in tightly-sealed containers.
Working alone
Certain extremely hazardous operations should not be performed if the PI or Lab Safety Contact(s) are
not present. Never work alone with extremely hazardous materials/operations. See the
Protocol/Procedure section below for specific prohibitions (if any) on working alone.
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.
Spill and Accident Procedure
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Chemical Spill Dial 911
Spill – Assess the extent of danger. Help 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 911 and 510-642-9090 for assistance.
Chemical Spill on Body or Clothes – Remove clothing and rinse body thoroughly in emergency shower
for at least 15 minutes. Seek medical attention. Notify supervisor and EH&S immediately. Follow up with
a call to 510-642-9090 to report the incident.
Chemical Splash Into Eyes – Immediately rinse eyeball and inner surface of eyelid with water from the
emergency eyewash station for 15 minutes by forcibly holding the eye open. Seek medical attention.
Notify supervisor and EH&S immediately. Follow up with a call to 510-642-9090 to report the incident.
Medical Emergency Dial 911
Life Threatening Emergency, After Hours, Weekends And Holidays – Dial 911 or go to the nearest
emergency room. Note: All serious injuries must be reported to EH&S within 8 hours. Follow up with a
call to 510-642-9090 to report the incident.
Non-Life Threatening Emergency – Go to the Occupational Health Facility (Tang Health Center). After
hours go to the nearest emergency room. Note: All serious injuries must be reported to EH&S within 8
hours. Follow up with a call to 510-642-9090 to report the incident.
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. Go to the Occupational Health Facility (Tang
Health Center). After hours go to the nearest emergency room. Note: All needle stick/puncture exposures
must be reported to EH&S within 8 hours. Follow up with a call to 510-642-9090 to report the incident.
Decontamination/Waste Disposal Procedure
NOTE: Lab-specific information on decontamination/waste disposal may be included in the
Protocol/Procedure section.
Wearing proper PPE, please decontaminate equipment and bench tops using soap and water. Please
dispose of the spent tetramethylammonium hydroxide and disposables contaminated with
tetramethylammonium hydroxide as hazardous waste.
General hazardous waste disposal guidelines:
Label Waste

Affix an on-line hazardous waste tag on all waste containers using the UCB Hazardous Waste
Program as soon as the first drop of waste is added to the container. Label all containers with
the label provided at http://ehs.berkeley.edu/hm/279-new-hazardous-waste-program-hwp.html. See the
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
EH&S Fact Sheet, “Hazardous Waste Management” for general instructions on procedures for
disposing of hazardous waste.
Safety Data Sheet (SDS) Location
SDS can be accessed online at http://ucmsds.com
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Protocol/Procedure (Add lab specific Protocol/Procedure here)
PPE and engineering controls as stated in the respective sections above. These controls are important,
as much care should be taken to avoid exposure. When transferring this reagent, a syringe must be used
for small volumes. Where necessary, a funnel must be used to assist with the transfer of larger quantities.
In the case of a spill, see the “Spill and Accident” section above.
Tetramethylammonium hydroxide
7
Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Protocol/Procedure
Preparation
Eliminate incompatible materials (acids and oxidizers) from the potential spill area.
Eliminate sources of ignition from the potential spill area.
Know the location of the nearest fire extinguisher, eyewash, and safety shower before beginning work.
Lab-specific
Information
(Add lab-specific information not included above if needed.)
Procedure/Use
Scale
1. Use of TMAH
25% in methanol
in reactions –
syringe transfer.
Up to 60 mL
tetramethyl
ammonium
hydroxide
solution per
addition
Engineering
Controls/Equipment
All work should be
performed in a fume
hood.
PPE (eye, face, gloves,
clothing)
Eye protection: Wear tightfitting safety goggles.
Face protection: Face shield
is not required for small
transfers.
Gloves: Wear reusable nitrile
gloves.
Clothing: Wear flame
resistant lab coat; full length
pants or equivalent; and closetoed and close-heeled shoes.
Tetramethylammonium hydroxide
8
Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Procedure Steps and Precautions
Use syringe to transfer. Use
established safe transfer methods.
Procedure/Use
Scale
2.
Use of TMAH
25% in methanol
in reactions –
graduated
cylinder and
funnel transfer
Up to 100
mL
tetramethyl
ammonium
hydroxide
solution per
addition
Engineering
Controls/Equipment
All work should be
performed in a fume
hood.
PPE (eye, face, gloves,
clothing)
Eye protection: Wear tightfitting safety goggles.
Face protection: Wear a face
shield if not fully protected by a
fume hood sash.
Gloves: Wear reusable nitrile
gloves.
Clothing: Wear flame
resistant lab coat; full length
pants or equivalent; and closetoed and close-heeled shoes.
Notes
Any deviation from this SOP requires approval from PI.
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Procedure Steps and Precautions
Use graduated cylinder and funnel
to transfer. Use established safe
transfer methods.
Tetramethylammonium hydroxide
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Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH
Documentation of Training (signature of all users is required)

Prior to conducting any work with tetramethylammonium hydroxide (TMAH), designated personnel
must provide training to his/her laboratory personnel specific to the hazards involved in working with
this substance, work area decontamination, and emergency procedures.

The Principal Investigator must provide his/her laboratory personnel with a copy of this SOP and a
copy of the SDS provided by the manufacturer.
I have read and understand the content of this SOP:
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Tetramethylammonium hydroxide
11
Date: 11/28/2012
SOP Template developed by The UC Center for Laboratory Safety
UCLA- EH&S
GKM/SH