Petroleum ether is a non-polar hydrocarbon mixture widely employed as a laboratory solvent in biochemistry for the selective extraction of lipids, waxes, and other non-polar metabolites from biological samples. Its volatility and hydrophobic character make it particularly suitable for analytical and preparative applications requiring efficient separation of neutral compounds.

Chemical Properties

Petroleum ether consists of volatile aliphatic hydrocarbons, primarily C5–C7 alkanes such as pentane, hexane isomers, and heptanes. Depending on the grade, typical boiling ranges include 35–60°C (light fraction), 60–80°C, or 100–120°C.

It exhibits low density (0.63–0.75 g/mL), negligible water solubility (<0.01%), and high vapor pressure, enabling rapid evaporation and efficient phase separation. Chemically inert and lacking functional groups, petroleum ether follows the principle of “like dissolves like,” making it highly effective for dissolving hydrophobic solutes.

Biochemical Applications

In lipid biochemistry, petroleum ether is commonly used for the sequential extraction of neutral lipids—including triglycerides and sterols—from Soxhlet-extracted or Folch-pretreated tissues. This process yields clean fractions suitable for thin-layer chromatography (TLC) or gas chromatography–mass spectrometry (GC-MS) prior to fatty acid profiling.

It is also applied in protein delipidation following recombinant expression to facilitate crystallization trials. Additionally, petroleum ether is used to wash chloroform phases to isolate pigments and carotenoids without co-extracting phospholipids.

In molecular biology workflows, low-boiling fractions are employed to accelerate drying of DNA pellets after ethanol precipitation or to remove mineral oil overlays from PCR reaction tubes.