Blood cadmium determination—results of an external quality assessment scheme

Abstract

Laboratory performance with respect to blood cadmium determination in the Guildford Trace Elements External Quality Assessment Scheme has been examined. Between March 1982 and September 1985 over 20 laboratories participated in the scheme and more than half submitted results regularly. A methodology survey showed that, whilst more laboratories used electrothermal atomic absorption spectrometry (ETA—AAS), sample pre-treatment, standardisation procedures and furnace temperature programmes varied enormously. Mean values for recovery of cadmium added to blood during each 6-monthly cycle were between 91 and 102% but varied more widely for individual samples (81–117%). Inter-laboratory coefficients of variation usually exceeded 20% at cadmium concentrations below 100 nmol l^–1(11.2 µg l^–1) but were lower (12–20%) at higher concentrations. No demonstrable changes in these parameters during the period of study were evident and it is concluded that laboratory performance with respect to cadmium analysis requires considerable improvement.