During proton-transfer reaction-mass spectrometry (PTR-MS) analysis, the air being analyzed is continuously pumped through a reaction chamber, where volatile organic compounds (VOCs) are ionized during proton transfer reactions with H3O+ ions. The ions produced are then measured with a mass analyzer. Analyses can be carried out on a variety of heritage objects (and their materials) such as graphic documents, natural history specimens, photographic or cinematographic films, synthetic polymers in design objects, varnishes or adhesives.
The transportable PTR-MS instrument of the CRC (VOCUS S TOFWERK) comprises:
- an ion source for high-purity (>98%) H3O+ ion production and a temperature-controlled and pressure-regulated reaction chamber
- a compact time-of-flight (ToF) analyzer with high resolution (m/Δm FWHM over 4000 for xylene) and high sensitivity (> 4000 cps/ppb for xylene in 1 minute), with an acquisition frequency of up to 40 Hz (25ms)
- an MCP detector enabling a low detection limit for xylene for an acquisition time of one minute (< 5 ppt)
- a hardware and software system for data acquisition under Igor Pro (WaveMetrics).