Scientific upcycling – Developing a SPME GC/MS methodology using anoxic chambers, for the monitoring of VOCs emitted from 3D polymeric artworks.
Mark Kearney / Dr. Joyce H. Townsend / Prof. Ivan Parkin / Manuel Hidalgo / Dr. Katherine Curran
Objects of art and design are commonly constructed, either partially or exclusively, from polymeric materials. As these objects have grown in cultural significance they have entered museum collections, however their long-term preservation within collectionscan be challenging . Currently, there are few options for in-situ decay monitoring of polymeric materials.
My talk will report on the development of a solid phase micro extraction gas chromatography mass spectrometry (SPME-GC/MS) methodology for the analysis of polymer samples under laboratory conditions. Monitoring the types of volatile organic compounds (VOCs) emitted from an object or present in its vicinity is a novel way to identify compositional or decay markers from the polymer.
The impetus for developing this methodology originates with limitations identified during previous analysis which aimed to ‘upscale’ the methodology proposed by Curran et al (2016) and move from the destructive analysis of VOC emissions from polymer samples to a non-destructive approach, analysing whole objects. Our previous research involved sealing small 3-dimensional polymeric objects into Tedlar® bags and allowing their VOC emissions to pre-concentrate within the bag for one week before analysis via SPME-GC/MS. Our results showed that this methodology allowed decay products such as acetic acid and furfural, and plasticisers such as camphor and dimethyl phthalate from the relevant polymer types to be detected by the SPME fibre. However, a number of limitations were found with this approach
A peak in the chromatogram for N,N-dimethyl-acetamide, which originated from the bag, overlapped with peak for styrene (used to detect polystyrene)
Phenol is emitted from the bag and therefore removes our ability to monitor its abundance (currently of interest in monitoring the decay of cellulose acetate)
The permeability of the bag limits pre-concentration time-lengths, limiting the methodologies use for lower emitting polymer types
The bags are single use and costly
We will develop a new methodology utilizing aluminium anoxic chambers which had been previously developed by Tate, London. The chambers measure 21 cm by 21 cm overall with a useable volume of approx. 923 cm3.
The chamber’s background VOCs will be analysed to ensure that any VOCs found within the chambers (from o-rings, inlet valves, etc.) are identified, taking particular note of any crossover with VOCs of specific interest to key degradation signs such as acids, aldehydes, and ketone.
Samples of naturally aged cellulose acetate (CA), which have been provided by the Smithsonian Institution, will be used to test the length of time needed for pre-concentration before SPME analysis. CA has been chosen due to its known VOC profile and its high emission rate. Cleaning regimes will be investigated in order to develop fast and efficient cleaning protocols between sample analysis. Oven heating to drive off VOCs along with solvent cleaning will be investigated. Finally, SPME exposure time inside the chamber will be investigated to determine the fibre equilibrium time length.
A successful methodology will be one where reliable capture of relevant VOCs from a sample, within a useable timeframe, is achieved and cleaning between samples is relatively easy.