Solvent · polar protic
Methanol CH4O
Also: MeOH
One of the two workhorse reversed-phase HPLC organic modifiers (with acetonitrile); low UV cutoff and low cost make it standard for RP gradient/isocratic separations; also normal-phase strong modifier, LC-MS mobile phase (protonation/ionization aid), and a common GC solvent/diluent and extraction solvent.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- CH4O
- CAS number
- 67-56-1
- UV cutoff
- 205 nm
- Snyder polarity index (P′)
- 5.1
- Selectivity group
- II
- Eluotropic strength ε° (silica)
- 0.73
- Boiling point
- 64.7 °C
- Viscosity (25 °C)
- 0.59 cP
- Refractive index (nD²⁰)
- 1.3284
- Density
- 0.792 g/mL
- Water miscibility
- miscible
- USP <467> class
- Class 2
Safety
- highly flammable (Flam. Liq. 2, flash point ~11-12 C)
- acute toxicity oral/dermal/inhalation (Acute Tox. 3)
- toxic to CNS and optic nerve - causes blindness/death if ingested (STOT SE 1)
- not a peroxide-former
- not classified as carcinogen
- some jurisdictions additionally flag suspected reproductive/developmental toxicity
Reference only. Solvents can be flammable, toxic, or peroxide-forming. Always consult the Safety Data Sheet (SDS) and your lab's protocols before handling.
What Methanol mixes with
Miscible with: 1-Propanol, 1,2-Dichloroethane, 1,4-Dioxane, 2-Propanol, Acetic acid, Acetone, Acetonitrile, Benzene, Carbon tetrachloride, Chloroform, Dichloromethane, Diethyl ether, Dimethyl sulfoxide, Ethanol, Ethyl acetate, Methyl ethyl ketone, Methyl isobutyl ketone, MTBE, n-Butanol, n-Butyl acetate, N-Methylpyrrolidone, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, tert-Butanol, Tetrahydrofuran, Toluene, Triethylamine, Water.
Partially miscible with: Cyclohexane, Iso-octane, n-Heptane, n-Hexane, n-Pentane — mix only over a limited range.
Check any specific pair on the interactive miscibility chart.
Using Methanol in HPLC/GC
One of the two workhorse reversed-phase HPLC organic modifiers (with acetonitrile); low UV cutoff and low cost make it standard for RP gradient/isocratic separations; also normal-phase strong modifier, LC-MS mobile phase (protonation/ionization aid), and a common GC solvent/diluent and extraction solvent.
Its Snyder polarity index is 5.1 (selectivity group II), and its UV cutoff of 205 nm is low enough for most UV detection.See what the polarity index means and the full UV cutoff table.
Sources
- University of Toronto (TRACES) — Burdick & Jackson — Solvent UV cutoff table (absorbance = 1 AU, 1 cm cell)
- Stenutz / L. R. Snyder — Solvent polarity index (P′) and selectivity groups
- NIST — Chemistry WebBook — thermophysical properties (BP, density, refractive index)
- PubChem (NIH/NLM) — Compound property records (physical constants, CAS, formula)
- USP <467> / ICH Q3C — Residual Solvents — solvent classification (Class 1/2/3)
Values are compiled from public references and were last verified July 2026. See ourmethodologyfor how we source and verify. Always confirm critical values against primary references and the SDS.