Factors affecting the practicality of solid-phase microextraction VOC analysis of artworks featuring polymeric materials in open environments

Abstract

Currently there is no proven method for in-situ monitoring of the decay progression of objects featuring polymeric materials. One potential method which is gaining traction, is the analysis of volatile organic compounds (VOC) via solid phase microextraction gas chromatography mass spectrometry (SPME-GC/MS). Few studies have focused on repeated, long-term monitoring of objects in open heritage environments via SPME-GC/MS. Specifically, the combined effects on methodological performance of the fibre exposure time in conjunction with the effects of variable environmental conditions over that period and fibre location with relation to the object have yet to be investigated. In order to study these effects, we tracked four key VOCs emitted from Naum Gabo's constructivist sculpture Construction in Space ‘Two Cones’ (Tate) by repeated SPME-GC/MS analysis. Five fibres in total were placed around the object and within its storage room. Two separate experimental campaigns were carried out, one exposing the fibres to the object for 1 Day, the other for 7 days. Our results show that an exposure time of 7 Days led to a lower relative standard deviation than for a 1 Day exposure time for each of the four VOCs. However, our results also show that the performance of individual fibres, at their specific locations, was better with an exposure time of 1 Day. Furthermore, we highlight the comparability of the background VOC profile to a location within the object's storage crate.The implications of our research are two-fold – firstly, when monitoring in an open environment, a shorter exposure time leads to more repeatable analysis over long time periods, however, it is at the expense of the ability to calculate concentrations as the fibre has not yet reached equilibrium. Secondly, background and object VOC profiles can be difficult to distinguish unless the fibre is in immediate vicinity of the point of interest.