## 3 Results and Discussions
### Future Perspectives  
This preliminary analysis of a range of modern reproducations of archaeological specimens indicates that the potential of GC\(\times\)GC-TOFMS to provide value for organic residue characterization is promising. Even in the absence of a robust HS-SPME optimization, notable volatile signatures could be investigated between the sample types analyzed. This also provides a potential avenue for a non-destructive analysis of the unaltered residue upon initial discovery, without requiring solvent extraction and/or derivitization. Although marker compounds cannot be extrapolated from this sample set, the analyses presented herein allowed for an evaluation of the general use of GC\(\times\)GC-TOFMS for organic residue characterization. Since the SPME-GC\(\times\)GC-TOFMS analysis is non-destructive, it can provide an additional tool to be incorporated in the analytical workflow of residue characterization, in addition to the vast array of instrumentation currently used for these purposes. There are a number of future avenues for this work to be further investigated. First and foremost, it would be valuable to begin analyzing replicate experimental samples to be able to apply robust statistical methods for the objective differentiation of residues. This must be done on lower quantities of residue in order to ensure the robustness of characterization strategies. Applying artificial aging of controlled experimental samples may also aid in improving characterization approaches in the future. In addition, the application of these techniques to additional archaeological specimens with complex histories would be interesting in order to determine if the experimental data can be extrapolated to real scenarios. In addition, the detection of compounds in this study was performed by low-resolution TOFMS. This affords the ability to perform mass spectral library searching and produce matches above a certain quality. However, in order to improve these identification, high-resolution mass spectrometry will be employed in the future. Some of the samples analyzed in this study contained extremely complex profiles, such as the resin samples that contained hundreds of components likely originating from plant materials within the resin or other additives. Differentiating compounds of this nature by low-resolution mass spectrometry can be difficult due to similarities in their produced spectra. GC\(\times\)GC coupled with high-resolution mass spectrometry has the potential to provide a higher degree of discrimination between these compounds and improve the identification confidence. We wish to thank Restek(r) Corporation, Trajan(r) Scientific and Medical, and Supelco Sigma-Aldrich(r) for providing us with GC phases and various consumables. [PERSON] is further acknowledged for his creation of the reference collection used in this study, and for providing the resin and bees wax mixtures. The research of [PERSON] is supported by Wallonie-Bruxelles International. The research of [PERSON] and [PERSON] is supported by the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 312283. [PERSON]-[PERSON] and [PERSON] conceived and designed the experiments; [PERSON], [PERSON], [PERSON] and [PERSON] performed the experiments; [PERSON], [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON] contributed reagents/materials/analysis tools; [PERSON] wrote the paper and [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] contributed to preparation and revisions of the paper. The authors declare no conflict of interest. The following abbreviations are used in this manuscript: