The extraction, quantification, and nature of hair lipid.

Synopsis A sensitive method is described for the spectrophotometric assay of hair lipid extracted from hair samples less than 10 mg in weight, i.e. for amounts of lipid down to about 5 mug. The solvent-free lipid extract is charred by heating in conc. sulphuric acid and the light absorbance of the acid is subsequently measured, after dilution, at 375 nm. Diethyl ether extracted only about one-third of the total hair lipid after 10 min at room temperature but this probably constitutes most of the surface hair lipid. Water-saturated ether heated under reflux extracted about two-thirds of the total lipid from hair which had been previously equilibrated in an atmosphere of 100% relative humidity. Saponified internal hair lipid was extracted after dissolution of the hair in aq. 2 M potassium hydroxide. Examination of the hair lipid extracts by thin layer chromatography and gas-liquid chromatography suggested that most of the internal lipid was of sebaceous origin.