Exploratory VOC analysis of Roman burial soils using SPME-HS-GC-MS: methodological considerations and interpretive constraints

Volatile organic compounds (VOCs) associated with decomposition have been widely studied in forensic contexts, yet their application to archaeological burial environments remains limited. This study presents an exploratory application of solid-phase microextraction-headspace sampling coupled with gas chromatography–mass spectrometry (SPME-HS-GC-MS) to Roman burial-associated soils from Fleet Marston, Buckinghamshire, UK. Sixteen sediment samples were collected from six Roman inhumation burial contexts. Sampling targeted cranial, pelvic, and pedal regions of the burial matrix, with comparative geological sediments sampled where excavation exposure permitted. The study does not seek to identify definitive biomarkers of human decomposition, but to assess whether SPME-HS-GC-MS can recover context-dependent volatile profiles consistent with long-term burial-related taphonomic processes. A restricted subset of putative VOCs, dominated by alkanes, aromatic hydrocarbons, and phenolic compounds were identified following exclusion of recurrent laboratory artefacts and blank-associated peaks. Many detected compounds are non-specific and may derive from converging biogenic, environmental, microbial, and material-derived degradation pathways, including soil organic matter transformation and possible coffin wood degradation. Similarities between burial and the comparative underlying geological sediments highlight the open-system nature of archaeological soils and the interpretive complexity of archaeological volatilomic assemblages over extended temporal scales. Nevertheless, patterned variation between burial contexts indicates that SPME-HS-GC-MS can recover volatile profiles reflective of chemically altered burial environments under defined analytical conditions. The results are presented as a methodological proof-of-concept and highlight both the potential and the interpretive constraints of applying VOC profiling to archaeological grave soils and necrosols.