###### Abstract  
Headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) have traditionally been used, in combination with other analyses, for the chemical characterization of organic residues recovered from archaeological specimens. Recently in many life science fields, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC\(\times\)GC-TOFMS) has provided numerous benefits over GC-MS. This study represents the first use of HS-SPME-GC\(\times\)GC-TOFMS to characterize specimens from an experimental modern reference collection. Solvent extractions and direct analyses were performed on materials such as ivory, bone, antlers, animal tissue, human tissue, sediment, and resin. Thicker film column sets were preferred due to reduced column overloading. The samples analyzed by HS-SPME directly on a specimen appeared to give unique signatures and generally produced a higher response than for the solvent-extracted residues. A non-destructive screening approach of specimens may, therefore, be possible. Resin and beeswax mixtures prepared by heating for different lengths of time appeared to provide distinctly different volatile signatures, suggesting that GC\(\times\)GC-TOFMS may be capable of differentiating alterations to resin in future studies. Further development of GC\(\times\)GC-TOFMS methods for archaeological applications will provide a valuable tool to uncover significant information on prehistoric technological changes and cultural behavior. HS-SPME; GC\(\times\)GC-TOFMS; volatile signature; archaeology; organic residues +
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0000-0001-6000-00001-6  
Many of the matrices suggested above are also challenging to analyze because they are comprised of a complex range of non-volatile, semi-volatile, and volatile components [2; 5]. The history of the sample only adds to this complexity, leading to the degradation of certain components and the potential for contaminant compounds to become present over time. A number of studies using one-dimensional gas chromatography (1D GC) have demonstrated the complexity of a vast range of modern reference and archaeological samples [1; 3; 9; 12; 13; 14]. In these studies, total ion current (TIC) chromatograms typically exhibit a large number of compounds with a broad dynamic range, and therefore may suffer from insufficient baseline separation of compounds. This could potentially lead to peaks that are obscured by co-elutions and, therefore, are not detected, or potentially peak misidentification using mass spectrometry. Derivatization is often used to reduce matrix effects [2; 5; 9]; however, many TIC chromatograms in published literature still exhibit poor baseline separation likely due to co-elution with an unresolved complex mixture (UCM) coming from the matrix. Co-elution of peaks at the detector can result in poor mass spectral library matches, which may result in the lack of an identity assigned to a peak, or in a more unfortunate scenario, may cause peak misidentification. The large number of trace components and UCM present in these chromatograms can also obscure baseline separation of components which may result in non-optimal quantification, especially in the absence of robust deconvolution algorithms. This can potentially impact age estimations when investigating degradation markers. It is proposed that characterization of archaeological samples would benefit substantially from the use of comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC\(\times\)GC-TOFMS). This comprehensive, multidimensional technique offers an improved peak capacity, leading to considerable enhancement in peak separation and subsequent quantification. GC\(\times\)GC is similar to 1D GC in most principles; however, it exploits the use of both a first dimension (\({}^{1}\)D) and second dimension (\({}^{2}\)D) column to produce two independent mechanisms of separation. The 1D separation is comparable to a conventional 1D GC run.