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Tetramethylammonium hydroxide solution

10 wt. % in H2O

N,N,N-trimethyl-methanaminium hydroxide, TMAH, TMAOH
Linear Formula:
CAS Number:
Molecular Weight:
MDL number:
PubChem Substance ID:

vapor pressure

17.5 mmHg ( 20 °C)

Quality Level


10 wt. % in H2O

refractive index

n20/D 1.3521


1.006 g/mL at 25 °C

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This Item

10 wt. % in H2O


25 wt. % in methanol


1.0 M±0.02 M in H2O


25 wt. % in H2O

refractive index

n20/D 1.3521

refractive index


refractive index

n20/D 1.3497

refractive index

n20/D 1.3806


1.006 g/mL at 25 °C


0.866 g/mL at 25 °C


1.005 g/mL at 25 °C


1.016 g/mL at 25 °C

Quality Level


Quality Level


Quality Level


Quality Level


General description

Tetramethylammonium hydroxide (TMAH), is a commercially available quaternary ammonium base with significantly higher basicity than ammonium hydroxide.


Tetramethylammonium hydroxide solution (10 wt. % in H2O) can be used as:      
  • A reactant to synthesize epoxy-polyhedral oligomeric silsesquioxanes (EPOSS) via sol-gel method using 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECTMS) in IPA.     
  • An ionic liquid to modify SnO2 nanocrystals, which are applicable as an efficient electron transport layer in perovskite solar cells.

TMAH can also be used as an anisotropic etchant for silicon due to its high silicon etching rate. The main advantage of using TMAH is that it causes no danger to electrical circuits due to the absence of alkali ions.

Signal Word


Hazard Classifications

Acute Tox. 3 Dermal - Acute Tox. 3 Oral - Aquatic Chronic 3 - Eye Dam. 1 - Skin Corr. 1B - STOT RE 1 Dermal - STOT SE 1

Target Organs

Central nervous system

Storage Class Code

6.1D - Non-combustible, acute toxic Cat.3 / toxic hazardous materials or hazardous materials causing chronic effects



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

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Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) enables the direct characterization of complex mixtures without prior fractionation. High mass resolution can distinguish peaks separated by as little as 1.1 mDa), and high mass accuracy enables assignment of
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Polymers, 13(10) (2021-06-03)
EPOSS of polyhedral oligomeric silsesquioxanes (POSS) mixture structure and LPSQ of ladder-like polysilsesquioxane (LPSQ) structure were synthesized via sol-gel reaction. EPSQ had a high molecular weight due to polycondensation by potassium carbonate. The EPSQ film showed uniform surface morphology due
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The aim of this study was to explore the synergies of laccase, a ligninolytic enzyme, with cellulose and hemicellulase amendments on ensiled corn stover. Molecular signals of lignin decomposition were observed by tetramethylammonium hydroxide thermochemolysis and gas chromatography-mass spectroscopy (TMAH-GC-MS)
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Potassium homeostasis is crucial for living cells. In the yeast Saccharomyces cerevisiae, the uptake of potassium is driven by the electrochemical gradient generated by the Pma1 H(+)-ATPase, and this process represents a major consumer of the gradient. We considered that
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A new water-soluble conjugated polymer containing fluorene and boron-dipyrromethene repeat units in the backbones (PBF) that exhibits red emission was synthesized and characterized. Cationic PBF forms uniform nanoparticles with negatively charged disodium salt 3,3'-dithiodipropionic acid (SDPA) in aqueous solution through

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