Abstract
Two mass spectrometry (MS) methods, solid-phase microextraction gas chromatography (SPME–GC–MS) and direct analysis in real time (DART-MS), have been explored to investigate widespread efflorescence observed on exhibited objects at the Smithsonian’s National Museum of the American Indian in New York (NMAI-NY). Both methods show great potential, in terms of speed of analysis and level of information, for identifying the organic component of the efflorescence as 2,2,6,6-tetramethyl-4-piperidinol (TMP-ol) emitted by the structural adhesive (Terostat MS 937) used for exhibit case construction. The utility of DART-MS was proven by detecting the presence of TMP-ol in construction materials in a fraction of the time and effort required for SPME–GC–MS analysis. In parallel, an unobtrusive SPME sampling strategy was used to detect volatile organic compounds (VOCs) accumulated in the exhibition cases. This sampling technique can be performed by collections and conservation staff at the museum and shipped to an off-site laboratory for analysis. This broadens the accessibility of MS techniques to museums without access to instrumentation or in-house analysis capabilities.
Highlights
Characterization of the efflorescence During the exploratory stage, Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM–EDS) analysis was used to investigate the elemental composition of the efflorescence
In order to better characterize the chemical composition of the efflorescence, Solid-phase microextraction (SPME)–Gas Chromatography (GC)–mass spectrometry (MS) and Direct Analysis Real Time (DART)-MS were applied in all efflorescence samples collected from the exhibition
Conclusions and future perspectives In this study, two mass spectrometry approaches, SPME–GC–MS and DART-MS, were used to investigate the efflorescence detected in a quarter of the objects exhibited in Infinity of Nations at the NMAI-NY
Summary
The first study focused on this issue, carried out by the Museum of Fine Arts, Boston (USA) and the University of Turin (Italy), suggested that the formation of this nonvolatile substance may have been caused by a reaction between the volatile 2,2,6,6-tetramethyl-4-piperidinol (TMP-ol) and an acidic compound, containing chlorine or sodium, present in the case environment [1, 2]. Tinuvin® 770 is an additive of the structural adhesive (Terostat) applied by the casework manufacturer from 2009 through 2014. According to the case manufacturer, two different formulations of the structural adhesive were used during the installation at NMAI-NYC: Terostat MS 937 (white and grey) and Terostat 9220 (black). Terostat is classified as modified silane polymer sealant with good capacity to bond various substrates together such as stainless steel, aluminum and other metals, glass, plastics, wood, and painted surfaces
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