CRITICAL COMPARISON OF WET AND DRY DIGESTION PROCEDURES FOR TRACE-METAL ANALYSIS OF MEAT AND FISH-TISSUES

The efficiency of four methods of digestion was evaluated for trace me tal analysis of pork meat and carp fish tissues. Two methods of dry an d two methods of wet ashing were compared in terms of calculated varia nces. Mixtures of HCl + HNC3 were applied for wet ashing of the sample s at 100 degrees C, while dry ashing with or without H2SO4 at 450 degr ees C were the alternative methods. The digests were subsequently anal ysed for Pb, Cd, Cu and Zn by graphite furnace atomic absorption spect rometry. Analysis of variance and Student's t-test were performed sepa rately for meat and fish analytical results. Wet digestion with a (1 1) mixture of HCl + HNO3 has given better recovery and repeatability for almost all metals than a (9 + 1) mixture of HCl + HNO3. Also betwe en the dry ashing methods, the use of H2SO4 has given better results t han ashing of the tissues without H2SO4.