n-Heptane is used in paints and coatings, as the rubber cement solvent and GC analysis, HPLC, spectrophotometry and environmental testing. Used as a primary reference standard in determining the knock rating of carburetor fuels and solvent especially for vegetable oils, low temperature thermo- meters, calibrations, and polymerization reaction medium. The hydroisomerization of n-heptane to form dibranched and tribranched products useful for producing high octane gasoline. water/AOT/n-heptane microemulsions plays an essential role for the synthesis, size control, and passivation of CdS nanoparticles.