Solvent · low polarity
MTBE C5H12O
Also: methyl tert-butyl ether, TBME
HPLC/GC extraction and normal-phase mobile-phase solvent; a low-boiling, low-viscosity ether used as a safer, lower-peroxide alternative to diethyl ether. Used in normal-phase LC to modulate polarity/retention, as an extraction solvent for lipophilic analytes (cholesterol, lipids, pesticides, carotenoids), for liquid-liquid extraction sample prep, and as a GC diluent. Notably UV-transparent for an ether (good baseline for UV detection), but drawbacks include peroxide formation, toxicity/environmental concern, and incompatibility with PEEK tubing.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- C5H12O
- CAS number
- 1634-04-4
- UV cutoff
- 210 nm
- Snyder polarity index (P′)
- 2.5
- Selectivity group
- I
- Eluotropic strength ε° (silica)
- 0.48
- Boiling point
- 55.2 °C
- Viscosity (25 °C)
- 0.34 cP
- Refractive index (nD²⁰)
- 1.369
- Density
- 0.7404 g/mL
- Water miscibility
- partial
- USP <467> class
- Class 3
Safety
- highly flammable (H225, flash point approx -28C)
- peroxide-former on air exposure (though less prone than diethyl ether)
- respiratory/skin/eye irritant (H315, H319/H320, H335)
- may cause drowsiness/dizziness (H336)
- possible groundwater contaminant / environmental concern
- IARC Group 3 (not classifiable as to carcinogenicity to humans)
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 MTBE mixes with
Miscible with: 1-Propanol, 1,2-Dichloroethane, 1,4-Dioxane, 2-Propanol, Acetic acid, Acetone, Acetonitrile, Benzene, Carbon tetrachloride, Chloroform, Cyclohexane, Dichloromethane, Diethyl ether, Ethanol, Ethyl acetate, Iso-octane, Methanol, Methyl ethyl ketone, Methyl isobutyl ketone, n-Butanol, n-Butyl acetate, n-Heptane, n-Hexane, N-Methylpyrrolidone, n-Pentane, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, tert-Butanol, Tetrahydrofuran, Toluene, Triethylamine.
Partially miscible with: Dimethyl sulfoxide, Water — mix only over a limited range.
Check any specific pair on the interactive miscibility chart.
Using MTBE in HPLC/GC
HPLC/GC extraction and normal-phase mobile-phase solvent; a low-boiling, low-viscosity ether used as a safer, lower-peroxide alternative to diethyl ether. Used in normal-phase LC to modulate polarity/retention, as an extraction solvent for lipophilic analytes (cholesterol, lipids, pesticides, carotenoids), for liquid-liquid extraction sample prep, and as a GC diluent. Notably UV-transparent for an ether (good baseline for UV detection), but drawbacks include peroxide formation, toxicity/environmental concern, and incompatibility with PEEK tubing.
Its Snyder polarity index is 2.5 (selectivity group I), and its UV cutoff of 210 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.