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 philippinarum by differential pulse anodic stripping voltammetry (DPASV) was carried 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 spectrometry (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 BCR-CRM 278. For all the elements the precision, expressed as relative standard deviation (s_r), and the accuracy, expressed as relative error (e), were in the order of 3 to 5%, while the detection limits were in the range 0.010–0.100 μg/g. The standard addition technique improved the resolution of the voltammetric method even in the case of very high element concentration ratios. The analytical procedure was used for real matrices sampled in the Adriatic Sea south to Po river mouth, in the zone “Goro bay”, and at open sea north to the Ravenna shore. Received: 7 June 1998 / Revised: 2 November 1998 / Accepted: 5 November 1998