Determination of Cd, Cu, Pb and Zn in woodlouse (Oniscus asellus)

The aim of this study was to assess the performance of selected destruction methods for the determination of heavy metals (Cd, Cu, Pb and Zn) in woodl ouse (Oniscus asellus). A vigorous total analysis involving microwave destr uction with HE HCl and HNO3 (method 1) was used as a reference method. Cons istently low values for the dry ashing method may indicate incomplete disso lution of the elements and/or losses through volatilisation. Method 3 (conc entrated HNO3) that frequently is used in literature, produced erroneous va lues for Cd, Cu and Pb. Results were consistent with the microwave digestio n, provided H2O2 was used during digestion (method 4, HNO3/H2O2). Method 5 (HNO3/HClO4, one destruction step) yielded low recoveries when only one des truction step was applied. Applying two destruction steps (method 6) result ed in values consistent with the microwave method, but was at the expense o f reproducibility and rendered the method more lengthy and laborious. Becau se of the very good performance combined with speed and simplicity, destruc tion with HNO3/H2O2 (method 4) emerged as the most convenient method.