Sorbent-coated metal discs for time-integrated VOC sampling: A reproducible workflow coupled to SPME–GC/MS

We describe a time-integrated platform based on sorbent-coated metal discs, formalized as a configurable architecture for VOC enrichment prior to gas chromatography/mass spectrometry (GC/MS) via secondary re-adsorption onto a solid-phase microextraction (SPME) fiber. A reproducible fabrication, conditioning, sampling, desorption, and re-adsorption protocol is specified, with a sorbent loading of approximately 0.2 g per 3.6 cm disc and sampling durations of 60 min. Across standard analysis replicates, the disc workflow produced higher GC/MS peak areas than direct SPME for most of the analytes, with reduced response for highly volatile compounds such as acetone. To explain this volatility-dependent behavior, we introduce a mass–transport competition framework in which the measurable signal is governed by the product of accumulated analyte mass and transfer efficiency, S = M_ads × η_transfer. The framework distinguishes the capacity-driven platform from equilibrium-based SPME. The described workflow is solvent-free, low-waste, reusable, and compatible with routine GC/MS instrumentation. Method overview: • Sorbent discs are prepared by covering a metal plate with a layer of sorbent material using a silicon adhesive. • Conditioned sorbent discs can be exposed to any gaseous samples. • Sorbent discs are heated to desorb the enriched VOCs that are subsequently re-adsorbed onto an SPME fiber to enable GC/MS analysis.