Influence of Sample Cleaning Prior to the Analysis on the Elemental Content of the Lichen Xanthoria parietina (L.) Th.Fr.

In this paper we investigated whether a different accuracy in sample cleaning prior to the analysis may affect the elemental composition of unwashed samples of the lichen Xanthoria parietina. To this purpose, samples of this lichen were collected from a remote area of Sardinia (Italy) and randomly divided into two aliquots, one cleaned very carefully (ca. 3-4 h to obtain ca. 200 mg of material for analysis) and the other cleaned with a lower efficiency (ca. 1-2 h). Samples were analysed by ICP-MS for the content of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, V and Zn. The results indicated that an accurate cleaning is effective for reducing the content of Al and Fe, i.e. soil-related elements, but that it has no effect on the concentrations of other elements less represented in the soil.