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4. Conclusions The research presents the results of two methods of analysis of volatiles emitted by office papers. Both begin with the extraction and preconcentration of the volatiles at room temperature, which were then desorbed from the SPME fiber and analyzed by a GC-TOF- MS instrument and a homemade electronic nose based on coated piezoelectric quartz crystals. Two sensors of the array, coated with PVP and THEED, respectively, enabled the discrimination of papers based on the tree used to obtain the wood pulp, as well as the identification of recycled paper. GC-TOF-MS analysis enabled the identification of the VOCs, and to find a few possible markers of the paper’s geographic origin. More samples should be included in a future study to validate these findings and build a robust model for paper identification, which could be useful for paper traceability for various purposes, including conservation, cultural heritage, forgery detection and other forensic applications, audits, the printing of official documents and new book editions. Supplementary Materials: The following supporting information can be downloaded at https: //www.mdpi.com/article/10.3390/s26072049/s1: Figure S1. Typical electronic nose response to desorbed volatile compounds from paper; Figure S2. Chromatogram of sample P13 obtained with a CAR/PDMS fiber; Figure S3. Chromatogram of sample P13 obtained with a PDMS fiber; Table S1. GC-TOF-MS compounds identification in papers from P1 to P21, using a CAR/PDMS fiber; Table S2. GC-TOF-MS compounds identification in papers from P1 to P21, using a PDMS fiber; Figure S4. Profile of volatile compounds obtained by SPME CAR-PDMS/GC-MS for each tested paper sample. Author Contributions: Conceptualization, M.T.S.R.G. Methodology, M.T.S.R.G.; Formal Analy- sis, M.I.S.V. and E.G.; Data Curation, M.I.S.V. and E.G.; Validation, M.I.S.V., E.G. and M.T.S.R.G. Writing—Original Draft Preparation, M.I.S.V., and M.T.S.R.G.; Writing—Review and Editing, E.G. and M.T.S.R.G. All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by national funds through FCT—Fundaç ã oparaaCi ê ncia e a Tecnologia I.P., under the project CESAM-Centro de Estudos do Ambiente e do Mar, with references UID/50017/2025 (doi.org/10.54499/UID/50017/2025) and LA/P/0094/2020 (doi.org/10.54499/LA/ P/0094/2020). Data Availability Statement: The original contributions presented in this study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author. Acknowledgments: The authors deeply acknowledge Carlos Silva (Chemical Engineer, The Navigator Company, Portugal) for providing paper samples from his private collection and technical informa- tion. The authors deeply acknowledge Pedro Antunes (Head of Organic Chemistry Lab., Ag ê ncia Portuguesa do Ambiente, APA) for allowing us to use the GC-MS equipment for chemical analysis. Conflicts of Interest: The authors declare no conflicts of interest.
References 1. Ervasti, I. Wood fiber contents of different materials in the paper industry material chain expressed in roundwood equivalents (RWEs). Silva Fenn. 2016 , 50 , 1611. [CrossRef] 2. Karlsson, H.; Fransson, I.; Österholm, H. Fiber Guide: Fiber Analysis and Process Applications in the Pulp and Paper Industry ; AB Lorentzen & Wettre: Stockholm, Sweeden, 2021. 3. Santos, A.J.A.; Anjos, O.M.S.; Sim õ es, R.M.S. Papermaking potential of Acacia dealbata and Acacia melanoxylon. Appita J. 2006 , 59 , 58–64. 4. Metsä Finland. Metsä Birch Bleached Hardwood Kraft Pulp/Metsä Fibre. Available online: https://www.metsagroup.com/ metsafibre/products-and-services/pulp/hardwood-pulp/metsa-birch/ (accessed on 22 March 2026). 5. Lattuati-Derieux, A.; Ramalho, O.; Egasse, C.; Thao-Heu, S.; Dupont, A.-L. Evaluation of solid-phase microextraction on-fiber derivatization for the analysis of paper degradation compounds. E-Preserv. Sci. 2015 , 12 , 38–49. 6. Strlicˇ, M.; Cigic´, I.; Kolar, J.; De Bruin, G.; Pihlar, B. Non-destructive evaluation of historical paper based on pH estimation from VOC emission. Sensors 2007 , 7 , 3136–3145. [CrossRef] [PubMed]
https://doi.org/10.3390/s26072049
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