ICES seventh round intercalibration for trace metals in biological tissue ICES 7/TM/BT (Part 2)

An ongoing series of ICES intercomparison exercises has been conducted since 1971 in order to examine results of analytical procedures used for the measurement of trace metals in marine biological tissues. The participants in these exercises \I/ere laboratories associated \1/ith the ICES fish and shellfish baseline and monitoring programs, those nominated by the Joint Monitoring Group of the Oslo/Paris Commissions, as \I/ell as others that had expressed an interest in participating in ICES projects, A gradual improvement in the level of agreement bet\1/een laboratories for the trace metals copper, zinc and mercury \I/as seen over the years, whereas little or no improvement

\I/as noted for cadmium and lead (Topping and Holden, 1978; Holden and Topping, 1981) by the end of the fifth exercise in 1979. The sixth ICES intercomparison study in 1980 \I/as concerned only w'ith cadmium and lead. It \I/as concluded from this study that most laboratories could produce reliable cadmium and lead values at the 1 and 2 mg/kg levels respectively, but only a small minority could analyze for lead at about 0.5 mg/kg (Topping, 1982). As a result, the ICES Marine Chemistry Working Group (MC'u/G) in 1981 (MCWG, 1981) appointed a sub-group \I/hose task \I/as to identify and try to resolve problems concerning the determination of lead in biological tissues. This sub-group confirmed the presence of matrix problems in the analysis using graphite furnace atomic absorption spectrometry and recommended procedures \llhich should enable confident analyses at the greater than 1 mg/kg level (Harms et al., 1982). Harms has recently expanded this \1/ork to sub mg/kg levels (Harms, 1985).