Relating volatiles analysis by GC–MS to Oddy test performance for determining the suitability of museum construction materials

Abstract

Conservators' decisions regarding the suitability of museum construction materials for use in proximity to artworks still rely heavily on accelerated corrosion tests like the Oddy test despite widespread criticisms. These issues include inconveniently long wait times, sensitivity to only those pollutants capable of tarnishing metals, a general sense of unreliability, exaggerated environmental conditions, and subjectivity in assessing the test's results. Increasingly, alternative strategies that use instrumental approaches involving volatiles sampling coupled to gas chromatography with mass spectrometry (GC-MS) are being explored as faster, more comprehensive, potentially quantitative, and possible more 'objective' means of assessing the dangers of off-gassing from museum construction materials. While many of these characteristics are now well documented, the objectivity of the instrumental result is arguable. While the detection of volatiles and semi-volatiles by GC-MS can confidently yield a list of potential pollutants, "chemical intuition" must be used to predict whether many of the emitted compounds can in fact adversely affect artwork. In this study, evolved gas analysis (EGA) coupled to GC-MS is used to predict the suitability of a small sample set of plastics for use in a museum. The potential impact of volatiles observed in the EGA chromatogram was assessed using chemical reactivity principles and the sparse literature data on the material damages caused by a small group of known pollutants. These same plastics were then tested using the British Museum's 3-in-1 Oddy test. The prediction based on an educated chemical assessment of the compounds identified through instrumental analysis shows good correlation with pooled results from the Oddy test. In one of the two instances of disagreement, the EGA analysis was actually overly conservative and leaned toward prohibiting or restricting a material that passed the Oddy test. In the other, a material that failed the Oddy test but was passed by instrumental analysis was later shown to contain VOCs that could be considered corrosive. This trial suggests that with practice and experience instrumental approaches may be useful to supplement and perhaps one day supplant traditional accelerated corrosion testing of museum construction materials.

Plastics in Heritage Collections: Poly(vinyl chloride) Degradation and Characterization

“…The analysis reported the emission of 2-ethyhexanol, 4-chlorooctane and 2-ethylhexyl thioglyconate, which is a by-product of organotin heat stabilizer. 161 However, EGA-GC-MS detects VOCs emitted at high temperatures, and it may not be representative of normal conditions of use.…”

Indoor Air Quality in Museum Display Cases: Volatile Emissions, Materials Contributions, Impacts

“…It has been proposed that for a given material, the volatiles analyzed by GC-MS could be evaluated in relation to the Oddy test performance, implying that the emissions from a material approved in the test will be safe in the museum environment. As already illustrated, a similar result cannot guarantee the absence of dangerous compounds [80].…”

Recent progress in instrumental techniques for architectural heritage materials

“…Gas chromatography-mass spectrometry (GC-MS) analysis is currently recognized as the best method for discriminating organic substances such as terpenic resins, waxes, proteins, drying oils and polysaccharide gums of micro-samples of painting layers. The method supplies elementary information for organic compounds, evaluating the optimal conditions for long-term conservation and planning restoration [308][309][310][311]. For example, Martinez et al [308] [309].…”