Novel nannofossils extraction methods from paintings, coupled with GC–MS for provenance determination and binder analysis

The use of calcareous nannofossils for provenance analysis is a new-old topic for cultural heritage. Several studies have already mentioned it for ceramic, but less for paintings. Preparatory layers of the paintings are often made with chalk, which is composed of microfossils. To extract a calcareous nannofossils assemblage from a painting layer, we need to disaggregate it. The method is to plunge the micro-samples into water and heat it if water alone does not work. The disaggregation process takes a long time and is not efficient in terms of quantitative results. In this work, we aimed to develop a disaggregation method that increases the number of determinable nannofossils extracted from a painting micro-sample. As these samples are valuable and unique, we decided that a combination of analyses on the disaggregated micro-sample should be tried to extract the most information from it. We studied the possibility of binder determination by gas chromatography–mass spectrometer after the nannofossils assemblage extraction on the residual liquid from the disaggregation. The method we are presenting is easy to apply, has a high disaggregation rate for most paintings, and a low impact on binders fatty acids for their determination.