Photothermal Desorption of Toluene from Carbonaceous Substrates Using Light Flash.

Area of Science:

• Analytical Chemistry
• Materials Science
• Occupational Health

Background:

• Millions of workers face occupational exposure to volatile organic compounds (VOCs) annually.
• Current VOC exposure assessment relies on sorbent preconcentrators with chemical or thermal desorption, each having limitations in sensitivity or sample reusability.
• Chemical desorption offers limited sensitivity (0.1% sample analysis), while thermal desorption provides maximal sensitivity but prevents sample reanalysis.

Purpose of the Study:

• To introduce and evaluate a novel photothermal desorption (PTD) technique for VOC analysis.
• To bridge the sensitivity gap between chemical and thermal desorption methods.
• To assess PTD performance using toluene on different carbonaceous substrates.

Main Methods:

• Photothermal desorption (PTD) was employed to partially desorb toluene from activated carbon powder (AC-p), single-walled carbon nanotube powder (SWNT-p), and SWNT felts (SWNT-f).
• Sorbents were loaded with 435 µg of toluene vapor and subjected to irradiation at varying light energies.
• Desorption efficiency was measured based on substrate type and light energy applied.

Main Results:

• Desorption efficiency ranged from less than 0.007% to 0.86% per flash, varying with substrate and irradiation energy.
• Photothermal desorption (PTD) performance was significantly higher and more consistent with SWNT felts (SWNT-f) compared to AC-p and SWNT-p.
• The enhanced performance of SWNT-f was attributed to its high thermal conductivity and interconnected matrix structure.

Conclusions:

• The novel photothermal desorption (PTD) technique effectively bridges the sensitivity gap in VOC exposure assessment.
• SWNT felts demonstrate superior performance as substrates for PTD due to their unique nanomaterial properties.
• PTD offers a promising alternative for sensitive and potentially repeatable analysis of VOCs in occupational settings.