Solvent · polar aprotic
Dimethyl sulfoxide C2H6OS
Also: DMSO
Polar aprotic solvent widely used as a sample-dissolution / injection solvent in reversed-phase HPLC for poorly soluble compounds (drug discovery, high-throughput screening stock solutions), and as a strong dissolving diluent for LC-MS sample prep. Used as the mobile-phase and standard solvent in GPC/SEC for polymers and polyamides. In GC it is a Class 3 residual solvent commonly quantified by headspace GC, and DMSO itself serves as a high-boiling matrix/dissolution solvent for headspace analysis. Rarely used as a mobile-phase component in NP-HPLC due to high viscosity and UV absorbance.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- C2H6OS
- CAS number
- 67-68-5
- UV cutoff
- 265 nm
- Snyder polarity index (P′)
- 7.2
- Selectivity group
- III
- Eluotropic strength ε° (silica)
- —
- Boiling point
- 189 °C
- Viscosity (25 °C)
- 2 cP
- Refractive index (nD²⁰)
- 1.4793
- Density
- 1.1 g/mL
- Water miscibility
- miscible
- USP <467> class
- Class 3
Safety
- combustible (flash point ~88-95 C; not highly flammable but combustible)
- skin penetration enhancer (readily absorbed through skin and can carry dissolved solutes systemically)
- mild skin/eye irritant
- hygroscopic
- not classified as carcinogen or reprotoxic
- low acute oral toxicity
- not a peroxide former
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 Dimethyl sulfoxide mixes with
Miscible with: 1-Propanol, 1,2-Dichloroethane, 1,4-Dioxane, 2-Propanol, Acetic acid, Acetone, Acetonitrile, Benzene, Chloroform, Dichloromethane, Ethanol, Ethyl acetate, Methanol, Methyl ethyl ketone, Methyl isobutyl ketone, n-Butanol, n-Butyl acetate, N-Methylpyrrolidone, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, tert-Butanol, Tetrahydrofuran, Triethylamine, Water.
Partially miscible with: Carbon tetrachloride, Diethyl ether, MTBE, Toluene — mix only over a limited range.
Immiscible with: Cyclohexane, Iso-octane, n-Heptane, n-Hexane, n-Pentane — these form two layers.
Check any specific pair on the interactive miscibility chart.
Using Dimethyl sulfoxide in HPLC/GC
Polar aprotic solvent widely used as a sample-dissolution / injection solvent in reversed-phase HPLC for poorly soluble compounds (drug discovery, high-throughput screening stock solutions), and as a strong dissolving diluent for LC-MS sample prep. Used as the mobile-phase and standard solvent in GPC/SEC for polymers and polyamides. In GC it is a Class 3 residual solvent commonly quantified by headspace GC, and DMSO itself serves as a high-boiling matrix/dissolution solvent for headspace analysis. Rarely used as a mobile-phase component in NP-HPLC due to high viscosity and UV absorbance.
Its Snyder polarity index is 7.2 (selectivity group III), and its UV cutoff of 265 nm limits low-wavelength 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.
Related solvents
Other selectivity group III to compare with Dimethyl sulfoxide.