Preliminary Study to Set up a Non Destructive In Situ Method to Monitor Soluble Salts Content in Stone Materials; The Usefulness of a Multivariate Approach

A new equipment and procedure to monitor in situ soluble salts content in stone materials were set up. They base on the extraction, by flowing deionized water, of soluble salts from stone surfaces and on the continuous registration of the real-time response of a conductivity probe; the resulting solution can be collected and then analyzed by ionic chromatography in the laboratory. A correlation between the signal obtained in situ and the chromatographic data was looked for; satisfying results were obtained but further investigation are needed in order to take into account all the involved parameters/variables and to extract the most significative index from the signal curve. Surely a multivariate approach will be of help to optimize both the equipment and the procedure. The engineering of the apparatus must be improved too.