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.