FINDINGS OF AN EXTERNAL QUALITY ASSESSMENT SCHEME FOR DETERMINING ALUMINUM IN DIALYSIS FLUIDS AND WATER

The analytical performance of laboratories participating in the dialys is fluids and water aluminum program of the Guildford External Quality Assessment Scheme over the period 1986-1993 has been reviewed. For al uminum concentrations >3.33 mu mol/L in dialysis fluids, the between l aboratory CV has fallen from similar to 36% to 23%, whereas for specim ens of water the reduction was from 36% to similar to 18%. Improvement s at lower concentrations were less impressive. Performance of individ ual participants varied; only a few consistently provided accurate res ults. Many of the participants are able to measure serum aluminum well , so lack of expertise is not responsible for poor results. We suggest that matrix effects associated with different specimen types have a s ignificant influence on performance and that due account is not always taken of these factors. Resolution of these problems would be aided b y appropriate reference materials.