A series of plasticised PVC tubing samples for blood contact applications were treated in a matrix experiment using different sterilisation procedures, prior to surface analysis of their inner lumens. The aim of this study was to determine the chemical compositions of the inner tubing walls (i.e. blood contact surfaces), in order to identify the changes introduced by the sterilisation processes. The following graph shows the variation in the surface coverage of DEHA / DEHP on the twelve inner PVC surfaces from different sources after different sterilisation procedures:

These results are initial plasticiser concentrations before blood contact. During renal dialysis procedures, approximately 60mg of DEHP are transferred into the blood of the patient per dialysis session from the PVC tubing. DEHP is rapidly metabolised but there is incomplete information on the final metabolites and whether they accumulate in specific organs. There is likely to be a lower accumulation of aromatic metabolite from DEHA than DEHP, due to the difference in the structures of the original plasticisers. Alternative plasticisers for medical grade plastics are regularly invested by XPS and SIMS for surface migration under standard sterilisation processes.