Characterization of proteinaceous and other organic materials in historical stringed musical instruments by off-line analytical pyrolysis with silylation

Historical stringed musical instruments such as violins, violas, and violoncellos are a unique class of cultural heritage objects. The production of these precious musical instruments reached its peak of prosperity in the 16-18th century in a northern Italy city, Cremona, represented by the great Masters of violin-making art. The multi-layered coating system and the pre-treatments applied to the surfaces of wood substrates are assumed to be related to the special sounds and esthetics of these antique instruments. However, due to the absence of written historical records, their construction and finishing methods are still a mystery. For this purpose, chemical an-alyses are useful to recover historical recipes by providing information about the material composition, methods of manufacture, and past restoration and maintenance procedures. Pyrolysis gas chromatography-mass spec-trometry provided useful information on material composition by using specific markers, but protein determi-nation remains an open analytical problem. A comprehensive study on various proteinaceous materials was undertaken to evaluate the performance of off-line pyrolysis combined with solid-phase microextraction with and without on-fiber silylation. The molecular markers were selected for each method. The methods were applied to historic instrument samples from Jacob Steiner, Luigi Baioni, Andrea Guarneri, Francesco Ruggeri, Lorenzo Storioni instruments and a violin from Piet`a of Venice. For the first time, the presence of proteinaceous materials was found by analytical pyrolysis in Stainer, Guarneri, Ruggeri, Storioni and probably Piet`a of Venice. Different combinations of the markers were observed in each specimen, with pyrocoll, diketopiperazines or silylated 3-hydroxypyridine the most common. Besides collagen, markers indicative of wood components (methoxy phenols, anhydrosugars), gums (anhydrosugars), and resins (dehydroabietic acid, larixyl acetate) provided a complete picture of the organic materials in stringed instruments obtainable by a single analysis of a micro-sample.

Automated summary

Historical stringed musical instruments like violins, violas, and violoncellos are considered as a distinctive class of cultural heritage items. The production of these precious instruments flourished between the 16th and 18th centuries in Cremona, a city in northern Italy known for its renowned Masters of violin-making art. The mysterious construction and finishing methods of these antique instruments, which contribute to their unique sounds and aesthetics, remain unknown due to the lack of written historical records. Chemical analyses, such as pyrolysis gas chromatography-mass spectrometry, have been employed to recover historical recipes and provide insights into the composition, manufacturing techniques, and past restoration and maintenance procedures. Through a comprehensive study on various proteinaceous materials and the evaluation of different analytical methods, including off-line pyrolysis combined with solid-phase microextraction, the presence of proteinaceous materials was discovered for the first time in instruments from famous makers like Jacob Steiner, Luigi Baioni, Andrea Guarneri, Francesco Ruggeri, Lorenzo Storioni, and possibly Piet`a of Venice. This research sheds light on the organic materials found in these stringed instruments and enhances our understanding of their construction and history.