Pretreatment and chromatographic analysis of phthalate esters, and their biochemical behavior in blood products

A method combining pretreatment by automated solid-phase extraction (SPE) with high-performance liquid chromatography (HPLC) has been developed for analysis of the endocrine disrupters mono-(2-ethylhexyl) phthalate (MEHP) and di-(2-ethylhexyl) phthalate (DEHP) in blood products. For successful analysis it was necessary to use acidified blood and acidified SPE eluent to suppress the ionization of MEHP and phthalic acid (PA). The amounts of PA, MEHP, and DEHP migrating into blood products from flexible blood bags made from poly(vinyl chloride) (PVC) was determined. By addition of inhibitors of endogenous blood lipase and esterase to blood it was shown that most of the MEHP detected in human plasma is not derived directly from flexible PVC bags but is produced by the action of these enzymes on DEHP. Esterase hydrolytic activity was greater than lipase activity.