Focus on analytical chemistry to illuminate the past

Abstract

Analytical chemistry has particularly significant importance in describing the composition of materials used or manipulated in the past. More widely, it is a fundamental part of archaeometry, a word coined in 1955 by Christopher Hawkes (he was Professor of European Archaeology at Oxford University) which originated from archaeology. Today it comprises all the scientific disciplines, technology, and methods used for extrapolating information from archaeological findings and contexts, and precious and artistic heritage objects. Archaeometry is thus the scientific study of the materials that make up objects, of organic and inorganic residues inside objects, and of the environments surrounding such objects. For such purposes and to establish the state of conservation, historians, archaeologists and art experts no longer look only at the visual appearance, the quality of patina, the weight and shape of ceramic pots, etc. They require sound scientific investigations as a means for acquiring information on the materials that make up the object and also for assessing decay. With this new knowledge restoration approaches can be planned and historical interpretation can be made. Consequently, over the last few years multi-disciplinary collaborations have flourished among researchers in archaeological sites, museums, conservation institutions, universities and scientific laboratories. To tackle any environmental or material problem safely and efficiently, reliable analytical methods are needed, with analysts working in interdisciplinary teams with archaeologists, biologists, pharmacists, and historians. Progress in analytical chemistry for archaeometry would especially benefit applications with diverse approaches and methods, and, above all, the continuous exchange of ideas. The reliability of analytical procedures adopted should be demonstrated by using certified reference materials. Because, in this field, they do not exist, laboratories should exploit round-robin exercises to demonstrate their expertise. Recent developments in analytical methods and procedures that are able to use very minute samples (a few micrograms), together with the increased availability of advanced analytical instrumentation, have led to great interest in the chemical study of materials found in archaeological or historical vessels related to various aspects of everyday life in past societies. There has been a particular focus on the characterization of organic materials occurring, for example, as the residues of food, cosmetics, medicines, and balms in archaeological potteries and mummies, of adhesives and waterproofing materials in shipwrecks, and of colorants in textiles and funerary practices. The chemical study of these materials rapidly provides a picture of the technology, social customs, diet, and rituals, in the context in which they were used. Their characterisation, if interpreted together with the information derived from the critical study of historical documents and of “in-situ evidence”, reveals the preparation, conservation, and uses of the substances investigated. Although it is certainly exciting to reveal the secrets of the past and to develop the long-term preservation of materials, the difficulties involved in characterising “cultural heritage samples” must still be born in mind. The very small size of samples, the mixtures of many materials, and the Published in the special issue Analytical Chemistry to Illuminate the Past with guest editor Maria Perla Colombini.