ADSORPTION-DESORPTION PROCESSES OF ALUMINUM, ZINC AND COPPER ON PLASTIC TUBING IN HEMODIALYSIS MONITORS

This study was performed to identify the source of contamination of di alysate with trace elements which had been observed in some haemodialy sis centres in Slovenia. A possible explanation of this phenomenon was adsorption-desorption processes occurring on the plastic tubing in wh ich dialysate was circulating in the haemodialysis monitors during dia lysis. To confirm this, contamination of tubing with trace elements wa s simulated in vitro. After contamination, acetate or bicarbonate dial ysates were prepared by the conventional procedure and samples of each dialysate collected in 1 mi fractions. Trace elements were measured b y atomic absorption spectrometry. The haemodialysis tubing was contami nated for 0.5 or 4.5 h with 1.85 or 7.41 mu mol/l of aluminium, 38.24 or 76.48 mu mol/l of zinc and 7.87 or 15.74 mu mol/l of copper. Steady state concentrations were reached after 5 min and ranged fbr aluminiu m from 0.18 to 0.67 mu mol/l, for zinc from 0.31 to 0.92 mu mol/l and for copper from 0.13 to 0.28 mu mol/l in acetate dialysate, and 0.15 t o 0.56 mu mol/l of aluminium, 0.46 to 1.53 mu mol/l of zinc and 0.06 t o 0.47 mu mol/l of copper in bicarbonate dialysate. The results sugges ted that adsorption-desorption processes are a probable source of cont amination of the dialysate that could affect the health of haemodialys is patients. (C) 1997 Elsevier Science B.V.