DIFFERENTIATION OF WILD OYSTERS FROM 3 SITES BY CHEMOMETRIC PROCEDURES

The total contents of twelve trace elements (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Hg and Pb) in the whole soft part of oysters (Ostrea edulis L.) sampled at two sites of the gulf of Trieste and at one site of the Grado Lagoon (Northern Adriatic Sea) were considered. The trace elements were determined in the dissolved ash obtained from 21 samples, by electrothermal atomic absorption spectrometry; mercury was determined by cold-vapour atomic absorption spectrometry after acid digestion. Oysters from the three sites were first differentiated by using discriminant analysis. The correlation matrix around the mean was used as the starting matrix for principal component analysis; dimensions were reduced to five principal components accounting for 84% of the total variance. A two-dimensional plot of the principal component scores was only partly successful in separating the oysters from the three different sites; a three-dimensional representation was satisfactory.