Distribution of di- and mono-(2-ethylhexyl) phthalate in human plasma

The distributions of di-(2-ethylexyl) phthalate and mono-(2-ethylhexyl) phthalate among the protein constituents of human plasma were studied by selective precipitation and chromatographic procedures. The distributions resulting from the leaching of phthalates from blood bags were simulated conveniently by allowing plasma to extract phthalates from coated Celite. More than 80 per cent of the diester was associated with lipoproteins, in the order: LDL greater than VLDL greater than HDL greater than chylomicrons. The remaining diester was apparently adsorbed weakly and nonspecifically to other proteins, including albumin. Mono-(2-ethylhexyl) phthalate was in equilibrium between free in solution and adsorbed to albumin; none was bound to lipoproteins. Extraction of phthalate from Celite into plasma should provide a convenient preparation for toxicity or pharmacokinetic studies.