Currently, there are few options for in situ non-destructive monitoring of the stability of modern polymeric materials within heritage collections. Past research has focused on exploiting the information contained in volatile organic compounds (VOCs) emitted from an object to understand decay mechanisms or identify the polymer composition (Lattuati-Derieux et al. 2013; Hakkarainen, Albertsson, and Karlsson 1997). The fundamental shortcoming of many previous studies utilising VOC capture is that often they use destructive analysis, elevated temperatures, artificially aged samples or combinations of these during analysis. While these studies have given us a wealth of information regarding decay profiles and key VOCs emitted from specific polymers, they often lack real-world applicability

Curran, K

Hidalgo, M

Kearney, M

Parkin, I

Townsend, JH

UCL Discovery

Full Terms & Conditions of access and use can be found athttp://www.tandfonline.com/action/journalInformation?journalCode=ysic20Studies in ConservationISSN: 0039-3630 (Print) 2047-0584 (Online) Journal homepage: http://www.tandfonline.com/loi/ysic20Characterisation of VOCs Surrounding NaumGabo’s Construction in Space ‘Two Cones’, (Tate) byin situ SPME GC-MS MonitoringMark Kearney, Ivan Parkin, Joyce H. Townsend, Manuel Hidalgo & KatherineCurranTo cite this article: Mark Kearney, Ivan Parkin, Joyce H. Townsend, Manuel Hidalgo & KatherineCurran (2018) Characterisation of VOCs Surrounding Naum Gabo’s Construction￿in￿Space￿‘TwoCones’, (Tate) by in￿situ SPME GC-MS Monitoring, Studies in Conservation, 63:sup1, 369-371,DOI: 10.1080/00393630.2018.1486530To link to this article:  https://doi.org/10.1080/00393630.2018.1486530© 2018 The Author(s). Published by InformaUK Limited, trading as Taylor & FrancisGroupPublished online: 11 Sep 2018.Submit your article to this journal Article views: 46View Crossmark dataPOSTERCharacterisation of VOCs Surrounding Naum Gabo’s Construction in Space ‘TwoCones’, (Tate) by in situ SPME GC-MS MonitoringMark Kearney 1, Ivan Parkin2, Joyce H. Townsend3, Manuel Hidalgo4 and Katherine Curran 11UCL Institute for Sustainable Heritage, University College London, London, UK; 2Department of Chemistry, University College London,London, UK; 3Conservation Department, Tate, London, UK; 4Arkema, Paris, FranceARTICLE HISTORY Received October 2017; Accepted April 2018KEYWORDS GC-MS; SPME; polymer degradation; VOC; modern materials; cellulose acetateIntroductionCurrently, there are few options for in situ non-destruc-tive monitoring of the stability of modern polymericmaterials within heritage collections. Past research hasfocused on exploiting the information contained in vola-tile organic compounds (VOCs) emitted from an objectto understand decay mechanisms or identify thepolymer composition (Lattuati-Derieux et al. 2013; Hak-karainen, Albertsson, and Karlsson 1997). The funda-mental shortcoming of many previous studies utilisingVOC capture is that often they use destructive analysis,elevated temperatures, artiﬁcially aged samples or com-binations of these during analysis. While these studieshave given us a wealth of information regarding decayproﬁles and key VOCs emitted from speciﬁc polymers,they often lack real-world applicability.Previous work by Curran et al. (2016) has shown thatit is possible to capture relevant VOC data from three-dimensional polymer objects at room temperatureusing solid phase microextraction gas chromato-graphy/mass spectrometry (SPME-GC-MS). However,this required pre-concentration of VOCs within Tedlarsealable bags, which introduces risks to the objectfrom poor handling during bagging, and severelylimits the size of objects which can be studied. Thenovelty of the method described here lies in usingSPME to undertake a systematic and repeated non-destructive and non-invasive monitoring programmeof multiple points-of-interest (POI) around a naturallyaged three-dimensional polymer object within itsnormal storage environment.The central questions this research aimed to answerwere –. Can key VOC markers for polymer composition ordecay be eﬃciently and conﬁdently detected usingSPME-GC-MS in a museum storage environment?. Can diﬀerences between the intensity of key VOCmarkers be detected from diﬀerent POIs aroundthe object?. Can insights into object material condition bedetected using SPME-GC-MS?. What is the potential impact for conservation prac-tice and VOC monitoring?Materials and methodsTwo experimental campaigns were carried out on theconstructivist sculpture Construction in Space ‘TwoCones’ (Tate T02143, 1936, this replica 1968) by theartist Naum Gabo. The work is available for studybecause it is deemed too deteriorated for display, andcurrently suﬀers, among other issues, from warping,crazing, and crystal growth (Figure 1(b)). As such anauthorised replica is being used instead for display(Lawson and Cane 2016). The sculpture is principallyconstructed from cellulose acetate (CA) and is currentlyloosely packed within a polymer storage crate lined withactivated charcoal cloth wrapped around Plastazotefoam, a Plastazote base, covered by fabric to preventdust accumulation, but not enclosed. During each cam-paign, POIs around the object (see Figure 1(a,b) forlocations) were examined by placing an exposed 50/30 μm DVB/CAR/PDMS SPME ﬁbre at each POI. A ﬁfthSPME ﬁbre was placed within the room housing theobject to measure the background VOCs present. Thetwo experimental campaigns diﬀered in the length oftime the SPME ﬁbre was exposed to the object. Onecampaign was exposed to the object for 24 hours, theother for 7 days. Three replicate measurements weremade during each campaign, on diﬀerent dates. Peakareas were normalised to the peak area of ethylbenzenefrom a MISA Group 17 Non-Halogen Organic Mix (SigmaAldrich 48133 Supelco) standard.© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis GroupThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricteduse, distribution, and reproduction in any medium, provided the original work is properly cited.CONTACT Mark Kearney mark.kearney.15@ucl.ac.uk UCL Institute for Sustainable Heritage, University College London, Central House, 14 UpperWoburn Place, London WC1H 0NN, UKSTUDIES IN CONSERVATION2018, VOL. 63, NO. S1, S369–S371https://doi.org/10.1080/00393630.2018.1486530ResultsThe results have shown that an exposure time of 24hours is adequate for the capture of VOCs relating topolymer composition and decay markers (Table 1).VOCs such as acetic acid and phenol, which relate todecay mechanisms, and the plasticisers diethyl phtha-late and dimethyl phthalate, were found at each ofthe POIs examined, though the concentration levelsvaried at each location.Another signiﬁcant result was the apparent diﬀer-ences between POI associated with areas of decayand those POI slightly further away. At both exposuretimes, the concentration of the four key VOCs, men-tioned above, was signiﬁcantly higher close to anarea with visible signs of decay as opposed to theﬁbres placed inside the storage crate but slightlyaway from the object – giving two distinct sets ofresults from the four ﬁbres places around the object.Possibly the most signiﬁcant insight was the cleardiﬀerence between the two areas of decay examined,suggesting diﬀerent decay mechanisms present on asingle object. The area where ﬁbre two was placedhad a signiﬁcantly higher ratio of phenol to aceticacid than where ﬁbre four was placed (Figure 2). Thisfeature was present for both 24 hours and 7 daysexposure times, though the ratio was less at 7 days(Table 1). Despite this diﬀerence in ratio, the overallconcentration of acetic acid was higher at ﬁbre fourthan at ﬁbre two. Visually, the area centred aroundﬁbre two appeared to be more heavily decayed andcontained more crystal growth on the polymersurface than ﬁbre four, which had virtually no crystalgrowth. FTIR analysis was performed on a crystalwhich had formed on the SPME ﬁbre housing,however, deﬁnitive identiﬁcation was not possible.Results suggested some form of phenyl phosphateplasticiser (tri- or diphenyl phosphate could not be dis-tinguished). These results are also backed up by pre-vious analysis on the object (Townsend, Angelova,and Ormsby 2016) which did show the presence of tri-phenyl phosphate (TPP). The high levels of phenolcould be explained by the work by Shinagawa, Mur-ayama, and Sakaino (1992) who proposed that thedecay of TPP, via hydrolysis, led to diphenyl phosphateand phenol. Our results are also in keeping with thoseof Tsang et al. (2009) who noticed that CA plasticisedFibre 5Fibre 3Fibre 4Fibre 2Figure 1. (a) Shows the POIs where the four ﬁbres were placed around the object. (b) Shows a close-up of the location of ﬁbre twoand the condition of the polymer surrounding it. Photos: Mark Kearney. Artwork © Nina and Graham Williams, DACS and Tate 2018.Table 1. Normalised peak area results from 24-hour exposure.Normalised peak area’s of 4 Key VOCs from 1-Day campaignAcetic acid Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5 Phenol Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5Set 1 0.29 0.07 0.01 0.27 0.16 Set 1 0.83 2.81 0.09 0.13 0.14Set 2 0.43 1.26 0.17 3.38 0.39 Set 2 1.60 6.77 0.32 1.31 0.49Set 3 0.24 0.83 0.26 2.07 0.32 Set 3 1.21 4.61 0.44 1.21 0.48Dimethyl Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5 Diethyl Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5Set 1 n/d 12.56 0.36 0.78 0.43 Set 1 0.20 5.90 0.23 0.24 0.23Set 2 n/d 16.58 0.94 14.06 2.01 Set 2 0.42 11.25 0.41 3.10 0.76Set 3 n/d 20.01 1.77 14.20 2.41 Set 3 0.42 9.48 0.72 3.70 0.85Normalised peak area’s of 4 Key VOCs from 7-Day campaignAcetic acid Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5 Phenol Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5Set 1 0.04 0.15 0.05 0.28 0.09 Set 1 1.05 3.53 0.59 3.31 1.46Set 2 0.08 0.16 0.08 0.21 0.06 Set 2 1.79 3.53 1.10 2.38 1.00Set 3 2.75 1.59 1.49 3.06 2.17 Set 3 10.98 10.44 6.09 7.30 6.75Dimethyl Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5 Diethyl Fibre 1 Fibre 2 Fibre 3 Fibre 4 Fibre 5Set 1 0.16 19.23 1.88 15.44 4.28 Set 1 0.60 13.69 0.78 7.24 1.38Set 2 0.24 19.60 3.10 13.03 3.25 Set 2 0.80 13.99 1.00 6.14 1.01Set 3 4.33 101.21 58.74 205.94 49.49 Set 3 20.44 126.94 21.76 104.83 17.56S370 M. KEARNEY ET AL.with TPP appeared to decay at a faster rate than CAwithout. Our results, therefore, heavily suggest thatwe are detecting two distinct decay mechanismsfrom the two diﬀerent areas. The higher levels ofacetic acid seen at ﬁbre four are generated by the dea-cetylation of CA, while hydrolysis of TPP leads to higherlevels of phenol.Taken together, these results suggest that SPME isan eﬃcient methodology for monitoring polymerobject decay. Our research also provides evidencethat monitoring of VOCs emitted from polymerobjects either needs to be targeted at speciﬁc POIsclose to the object, or else generally, with the under-standing that VOC ‘hot spots’ may be missed.Our work highlights the capabilities of SPME-GC-MSto detect potential diﬀerences in decay mechanismsfrom a single object. Our work also adds further evi-dence to the theory that CA plasticisers with TPPdecay at a faster rate than other forms of the material.There is also a potential impact for collection care, asour research suggests that current storage practices,such as open storage and charcoal inhibitors forhighly decayed polymer objects are insuﬃcient foreliminating VOC build-up in certain areas. Our researchpoints towards the need for better control of the ven-tilation of troublesome polymer objects kept at roomtemperature – this would likely take the form of aninvasive procedure such as a continuous air ﬂow overthe object or periodic ﬂushing of the atmospherearound the object.Disclosure statementNo potential conﬂict of interest was reported by the authors.FundingThis project has received funding from the European Union’sHorizon 2020 research and innovation programme (H2020European Research Council) under grant agreementnumber 646063 and also this work was supported by Engin-eering and Physical Sciences Research Council: [grant numberEP/L016036/1].ORCIDMark Kearney http://orcid.org/0000-0002-3986-1153Katherine Curran http://orcid.org/0000-0001-7169-3359ReferencesCurran, K., M. Underhill, L. T. Gibson, and M. Strlič. 2016. “TheDevelopment of a SPME-GC/MS Method for the Analysis ofVOC Emissions from Historic Plastic and Rubber Materials.”Microchemical Journal 124: 909–918. doi:10.1016/j.microc.2015.08.027.Hakkarainen, M., A.-C. Albertsson, and S. Karlsson. 1997. “SolidPhase Microextraction (SPME) as an Eﬀective Means toIsolate Degradation Products in Polymers.” Journal ofEnvironmental Polymer Degradation 5 (2): 67–73. http://link.springer.com/10.1007/BF02763589.Lattuati-Derieux, A., C. Egasse, S. Thao-Heu, N. Balcar, G.Barabant, and B. Lavédrine. 2013. “What Do Plastics Emit?HS-SPME-GC/MS Analyses of New Standard Plastics andPlastic Objects in Museum Collections.” Journal ofCultural Heritage 14 (3): 238–247. doi:10.1016/j.culher.2012.06.005.Lawson, L., and S. Cane. 2016. “Do Conservators Dream ofElectric Sheep? Replicas and Replication.” Studies inConservation 61 (S2): 109–113. doi:10.1080/00393630.2016.1181348.Shinagawa, Y., M. Murayama, and Y. Sakaino. 1992.“Investigation of the Archival Stability of CelluloseTriacetate Film: The Eﬀect of Additives to CTA Support.”Postprints of Polymers in Conservation 105: 138–150.Townsend, J. H., L. Angelova, and B. Ormsby. 2016. “T02143Analysis 2016.” Unpublished Tate analysis report.Tsang, J., O. Madden, M. Coughlin, A. Maiorana, J. Watson, N.Little, and R. Speakman. 2009. “Degradation of ‘Lumarith’Cellulose Acetate: Examination and Chemical Analysis ofa Salesman’s Sample Kit.” Studies in Conservation 54: 90–105.Ratio of Phenol To Acetic acid for 24-Hour analysisFibre 2 - Black ---- Fibre 4 - Grey051015202535304045Set 1 Set 2 Set 3Ratio of Phenol To Acetic acid for 7-Day analysisFibre 2 - Black ---- Fibre 4 - GreySet 1 Set 2 Set 30510152025Figure 2. Ratios of phenol to acetic acid for the two exposures. Not the consistent high levels of phenol recorded by ﬁbre two (inblack) compared to ﬁbre four (in grey). This suggests that there is something additional driving the emission of phenol in the areacovered by ﬁbre two.CHARACTERISATION OF VOCS BY IN SITU SPME GC-MS MONITORING S371

Characterisation of VOCs Surrounding Naum Gabo’s Construction in Space ‘Two Cones’, (Tate) by in situ SPME GC-MS Monitoring

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Characterisation of VOCs Surrounding Naum Gabo’s Construction in Space ‘Two Cones’, (Tate) by in situ SPME GC-MS Monitoring

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