Extract fresh leaf tissue of a test plant by maceration with 20 volumes of cold isopropanol to deactivate the hydrolytic enzymes. Re-extract the residue with a mixture of chloroform-methanol (2:1, v/v). Grind the seeds to a coarse powder and extract it with chloroform-methanol (2:1, v/v) or with light petroleum. If lipids are tightly bound to the seed tissue, use the chloroform-ethanol-water (20:9.5:0.5) mixture for their extraction. The extracted material must be stored at 4°C to avoid oxidation or in the presence of an antioxidant (e.g. 0.005% butylated hydroxy toluene, BHT).
Alkanes are long-chain hydrocarbons distributed in the waxy coating film on the surface of leaves and fruits in plants . They are constituents of waxes. These with cutin, constitute the hydrophobic cuticle which limits water loss, controls gaseous exchange and participates in the protection against pathogenic agents. Waxes are a mixture of hydrocarbons, free and hydroxylated aliphatic acids, aliphatic alcohols, aliphatic aldehydes and aliphatic ketones, b-diketones and esters. They can also contain terpenoids and flavonoids.
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