SLURRY PREPARATION BY HIGH-PRESSURE HOMOGENIZATION FOR CADMIUM, COPPER AND LEAD DETERMINATION IN CERVINE LIVER AND KIDNEY BY ELECTROTHERMALATOMIC-ABSORPTION SPECTROMETRY

Homogenization with a flat valve homogenizer in combination with high- speed blending was evaluated for the preparation of slurries suitable for the ETAAS determination of cadmium, copper and lead concentrations in six SRMs and in frozen cervine liver and kidney,Fresh tissue (appr oximately 2 g) or powdered SRM (approximately 0.1 g) was dispersed, at high speed, in 20 ml of ethanol-water (1 + 9 v/v) containing 0.25 % m im tetramethylammonium hydroxide, The resulting suspension was passed through a high-pressure flat valve homogenizer, Determinations perform ed on the resulting homogenate, provided estimates for Cd, Pb and Cu c oncentrations that were within 27, 23 and 18% of the certified values, respectively, for the six SRMs. In all instances, the experimental re sults did not differ significantly from the certified values, For froz en tissues there was good agreement between the concentrations as dete rmined by slurry homogenization-ETAAS and conventional digestion-ICP-M S, In addition, no significant differences were detected between the s lopes of the calibration curves for external standards and standard ad ditions to homogenized sample (SRMs or fresh tissue), Moreover, replic ate determinations of analyte concentrations in slurries at various ti mes post-preparation did not detect any segregation of the homogenates during 6 d, For these matrices at least, short-term sample storage ha d no discernible effect on the analyte apparent concentrations, The ap plicability of the process was limited only by the levels of contamina ting Pb and Cu introduced into the sample by the homogenizer.