No sampling, the best sampling. Noninvasive and micro-invasive strategies for cultural heritage studies.

TASCÓN, MARCOS; GHECO, LUCAS; CASTELLÁ, FLORENCIA; AHETS ETCHEBERRY, EUGENIA; MASTRANGELO, NOEMÍ; SOTO, SABRINA; LANDINO, MATÍAS; GIUNTINI, LORENZO; TACCETTI, FRANCESCO; MARTE, FERNANDO

Conferencia; 1st European Sample Preparation e-Conference; 2021

EuChemS

Materiality of cultural heritage objects has become an analytical challenge. This is not only due to the well-known limited amount of sample that can be taken but also due to less visible drawbacks such as film and sample heterogeneity. The latter, laying on the basis that cultural heritage cannot be considered as a bidimensional entity but a tridimensional one,is usually composed by a complex overlapping of different micrometric layers [1,2]. In this work is presented the recent advances of the group in this regard for different applications in rock art, modern art and classical canvas paintings. Interestingly, the selected analytical strategies will strongly depend on the research question, going from a simple noninvasive analysis to a deep layered organic and inorganic characterization.Regardless of this complexity, in agreement with the concept of ?no sampling?, the first approach always consists of the screening of the object with noninvasive analytical techniques (Figure 1). In respect of this point, the group has developed a 3D X-Ray Fluorescence scanner (XRF) allowing for elemental characterization [3]. The XRF scanner allowed to get crucial information about inorganic information as well as abnormalities in the object as repainting, modifications done by the artist, and different paint layer overlapping. In addition, multispectral, UV, X-Ray transmission, among other techniques are also implemented to attain indirect information about chemical composition.Nevertheless, the information collected by noninvasive approaches is not always suitable and sampling is needed. To this end, the sampling conditions must be extremely conservatives and, at the same time, representatives. Here, sample preparation of minute samples considering a layered or bulk analysis will clearly differ. On the one hand, for layered analysis (figure 1), cross-sections exposing all its constitutive strata are prepared followed by different µ-spectroscopic analyses [1,2]. On the other hand, as evidenced in figure 1, bulk analysis often dedicated to detailed organic composition determination implies the extraction, derivatization and sometimes preconcentration of these samples [4]. The work allowed to find molecular time markers employed for industrial paint relative dating in works of art. In this way, a series of advances and investigations are presented where the avoidance or minimization of sample size is required.