Gel filtration of phthalate esters

Abstract Calibration of the gel-filtration system polystyrene beads—benzene is effected in terms of the molecular weights of solutes without using a void volume indicator. Correction for dead volumes is made by incorporating in the loads a dye producing a peak of accurately known elution volume to serve as reference point on a strip-chart absorption diagram of column effluent. The calibrated column separates small amounts of plasticizer phthalate esters from excess of lipids extracted from biological materials, providing evidence of identity in samples sufficiently pure for estimation by gas chromatography. Further purification can, where necessary, be achieved quantitatively by high-performance liquid chromatography on silicic acid with 2% (v/v) diisopropyl ether in n -hexane as mobile phase.