Detection of volatile organic compounds in airtight exhibition spaces by GC–MS using two complementary injection techniques

A novel method was developed and optimized for the determination of volatile organic compounds (VOCs) inside an airtight exhibition case used for the storage and display of museum artifacts. The method uses a static headspace module coupled to a gas chromatograph/mass spectrometer. In this method, the air is sampled by passive samplers (coconut shell charcoal and synthetic charcoal). In the laboratory, the VOCs are thermally desorbed (120 min, 60 °C) in the HS furnace after the addition of a small volume of dimethylacetamide (DMA). The VOCs present in the gas phase are then automatically analyzed by GC–MS. The information obtained is complemented by the analysis of the DMA liquid phase by direct injection GC–MS in the same chromatograph. The VOCs are identified by studying the mass spectra obtained by both techniques. This approach provides an economically viable, non-invasive and visually non-disruptive solution for VOC detection in enclosed spaces in museum environments. The use of two complementary injection techniques allows for good detection and suitable chromatographic response to a wide range of volatile compounds. This method was applied for the identification of VOCs present in an enclosed airtight exhibition case at the Museu Nacional d'Art de Catalunya (MNAC), where the formation of efflorescence was observed on the surface of a Modernist jewel displayed inside, as it was suspected that VOCs were the main cause for the degradation. Forty-five different VOCs were detected and identified inside the exhibition case: thirteen of them by HS–GC–MS, fifteen of them by direct injection GC–MS, and seventeen by both techniques. Among the most relevant VOCs identified, acetic acid, acetaldehyde and formaldehyde stand out due to the danger they pose to museum artifacts exposed in enclosed spaces, especially in the long term.