Determination of heavy metals in environmental bio-indicators by voltammetric and spectroscopic techniques

The determination of copper, lead, cadmium and zinc in matrices involved in the food chain as algae, species Ulva rigida, and clams, species Tapes phi lippinarum by differential pulse anodic stripping voltammetry (DPASV) was c arried out. For the mercury determination in these matrices, a new accurate and precise method was developed employing a mixture of concentrated acids H2SO4-K2Cr2O7 for digestion and subsequent cold vapor atomic absorption sp ectrometry (CV-AAS) by reduction with SnCl2. The analytical procedures were verified for four reference standard materials: Ulva lactuca BCR-CRM 279, Lagarosiphon major BCR-CRM 060, Oyster tissue NBS-SRM 1566, Mussel tissue B CR-CRM 278. For all the elements the precision. expressed as relative stand ard deviation (s(r)), and the accuracy, expressed as relative error (e), we re in the order of 3 to 5%, while the detection limits were in the range 0. 010-0.100 mu g/g. The standard addition technique improved the resolution o f the voltammetric method even in the case of very high element concentrati on ratios. The analytical procedure was used for real matrices sampled in t he Adriatic Sea south to Po river mouth, in the zone "Goro bay", and at ope n sea north to the Ravenna shore.