Passage through a silica gel column greatly reduces the ultraviolet absorption of n- (CAS NO. ). (The silica gel is previously heated to 350 °C before use.) For more extensive purification, heptane is shaken with successive small portions of conc H₂SO₄ until the lower (acid) layer remains colourless. The heptane is then washed successively with water, aq 10% Na₂CO₃, water (twice), and dried with CaSO₄, MgSO₄ or CaCl₂. It is distd from sodium. n-Heptane can be distd azeotropically with methanol, then the methanol can be washed out with water and, after drying, the heptane is redistd.

Other purification procedures include passage through activated basic alumina, drying with CaH₂, storage with sodium, and stirring with 0.5N KMnO₄ in 6N H₂SO₄ for 12h after treatment with conc H₂SO₄. yl-containing impurities have been removed by percolation through a column of impregnated Celite made by dissolving 0.5g of 2,4-dinitrophenylhydrazine in 6mL of 85% H₃PO₄ by grinding together, then adding 4mL of distilled water and 10g Celite.