Matrix effects in the determination of aluminium in dialysis fluids by graphite furnace atomic absorption spectrometry

Abstract

The effect of various salts on the GFAAS determination of aluminium in renal and peritoneal dialysis fluids was evaluated. Although calcium chloride produced the most marked interference other chlorides also depressed the aluminium signal. The day-to-day variation between calibration graphs was considerable and therefore, initially, a single matrix-adjusted standard was used. Modification of the furnace programme to employ shorter ramp times for the drying and pre-treatment stages together with the introduction of orthophosphoric acid as a matrix modifier were shown to eliminate matrix effects. A simple non-adjusted aluminium standard could be used and the method was applicable to both dialysis fluids and raw materials. Three batches of peritoneal dialysis fluid were analysed with satisfactory precision and contained aluminium levels between 8.43 and 9.06 µg l^–1 and three batches of renal dialysis fluid contained between 9.11 and 10.05 µg l^–1 of aluminium, all well within the accepted limits.