Chromatography Solvent

Solvent picker by polarity index for TLC and HPLC mobile phases.

How to use this tool

Find a solvent of the right strength for a TLC or column mobile phase. The table ranks common solvents by how hard they push compounds along on silica.

What to enter

Filter: optional. Type a solvent name (hexane, ethyl acetate) to find one, or the words polar / nonpolar to narrow the list. Leave it empty to see the whole series.

Reading the result

Solvents are listed weakest at the top, strongest at the bottom on silica (normal phase), invert for C18 reverse phase. ε° (silica) is eluotropic strength (higher = elutes faster), P′ is the polarity index, plus boiling point and whether it mixes with water. Start non-polar and blend in a stronger solvent until your spot reaches R_f ≈ 0.3–0.5.

Worked example

On silica, hexane sits at the weak end (ε° 0.01) and methanol near the strong end (ε° 0.95); a hexane/ethyl-acetate blend tunes anything in between.

Solvents ranked by eluotropic strength on silica (normal phase). Higher ε° = more polar = elutes faster on silica. Reverse the order for reverse-phase (C18).

Filter

Type a solvent name, or "polar" / "nonpolar" to narrow the series. Leave empty to see all.

Choosing a mobile phase

For silica TLC, start non-polar and add a polar modifier until your spot reaches R_f ≈ 0.3–0.5. A common gradient is hexane/ethyl acetate; tune the ratio rather than switching systems. Eluotropic strength (ε°) is the adsorption energy on alumina/silica, a practical ranking of how strongly each solvent pushes compounds up the plate.

Sources

Snyder eluotropic series (silica); Reichardt solvent polarity tables.
Still et al., flash chromatography (J. Org. Chem. 1978).