Invasive and Not Invasive Analysis of Soluble Salts in Stones; Look For Correlation in the Case Study of the Todi Cathedral Floor

Two non invasive methods and the UNI 11087/2003 method [1] for the determination of soluble salts content in stones were compared looking for correlation between obtained data. Three different kind of stone, constituting the Todi Cathedral floor, were considered. Ionic chromatography (IC) and Inductively Coupled Plasma (ICP) were used for the determination of anions and cations respectively; pH, conductivity and redox potential (ORP) measurements were also performed. Samples were characterised by Scanning Electron microscopy coupled with X-ray microanalysis (SEM/EDS) and X-ray diffraction (XRD). Density and porosity were also determined, the second by a new methodological approach (running research). Interesting results can be drawn by the very big mole of obtained data; surely it would be better evaluated by chemometrics or multivariate analysis.