oa Biomass Burning Tracers: Methodological Refinement and Comparative Evaluation of LC-MS/MS and GC-MS

This study refines monosaccharide anhydrides (MAs) analysis, crucial tracers of low‑temperature smoldering fires often missed by PAHs based proxies. An optimized LC‑MS/MS workflow, featuring improved chromatographic resolution and selective MRM transitions, eliminates previous isomeric misassignments and delivers precise identification and quantification. Validation with commercial standards and a lacustrine sediment extract confirms method accuracy. Comparative stability tests demonstrate pronounced MAs loss after BSTFA derivatization and GC‑MS re‑analysis (levoglucosan −24 ± 6 %, mannosan −40 ± 3 %, galactosan −23 ± 10 % in six months). Underivatized aliquots processed by LC‑MS/MS exhibit negligible change (≤ 8 %), underscoring superior reproducibility. Operationally, LC‑MS/MS attains high throughput (≈ 20 samples day⁻¹), requires only solvent exchange plus internal‑standard spiking, and shortens instrument runtime. GC‑MS remains valuable as an orthogonal validation tool but entails labor‑intensive derivatization, longer runtimes, higher reagent cost and reduced throughput, limitations for high‑frequency or large‑scale monitoring. Integrating LC‑MS/MS precision with GC‑MS cross‑verification yields a versatile analytical framework for paleofire reconstruction, atmospheric chemistry and air‑quality assessment, linking historical sedimentary records to present‑day aerosol composition while addressing combustion impacts on Earth‑system processes.