Solvent · water
Water H2O
Also: H2O, aqueous
Primary aqueous component of reversed-phase HPLC mobile phases; blended with methanol or acetonitrile (plus buffers/ion-pair reagents/acids) for isocratic and gradient elution. Used as sample diluent and blank. LC-MS grade water is standard. Not a GC carrier; occasionally a headspace/sample matrix.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- H2O
- CAS number
- 7732-18-5
- UV cutoff
- 190 nm
- Snyder polarity index (P′)
- 10.2
- Selectivity group
- VIII
- Eluotropic strength ε° (silica)
- —
- Boiling point
- 100 °C
- Viscosity (25 °C)
- 0.89 cP
- Refractive index (nD²⁰)
- 1.333
- Density
- 0.998 g/mL
- Water miscibility
- miscible
- USP <467> class
- not classified
Safety
No special hazard flags in our dataset — but always read the SDS.
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 Water mixes with
Miscible with: 1-Propanol, 1,4-Dioxane, 2-Propanol, Acetic acid, Acetone, Acetonitrile, Dimethyl sulfoxide, Ethanol, Methanol, N-Methylpyrrolidone, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, tert-Butanol, Tetrahydrofuran.
Partially miscible with: Diethyl ether, Ethyl acetate, Methyl ethyl ketone, MTBE, n-Butanol, Triethylamine — mix only over a limited range.
Immiscible with: 1,2-Dichloroethane, Benzene, Carbon tetrachloride, Chloroform, Cyclohexane, Dichloromethane, Iso-octane, Methyl isobutyl ketone, n-Butyl acetate, n-Heptane, n-Hexane, n-Pentane, Toluene — these form two layers.
Check any specific pair on the interactive miscibility chart.
Using Water in HPLC/GC
Primary aqueous component of reversed-phase HPLC mobile phases; blended with methanol or acetonitrile (plus buffers/ion-pair reagents/acids) for isocratic and gradient elution. Used as sample diluent and blank. LC-MS grade water is standard. Not a GC carrier; occasionally a headspace/sample matrix.
Its Snyder polarity index is 10.2 (selectivity group VIII), and its UV cutoff of 190 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.