On-filter derivatisation and alkaline trap sampling for UAV-based gas-phase halogen speciation in volcanic plumes

Area of Science:

• Atmospheric Chemistry
• Volcanology
• Analytical Chemistry

Background:

• Volcanic halogen emissions significantly impact atmospheric chemistry and indicate volcanic activity.
• Accurate in situ quantification and speciation of reactive halogen species (RHS) are analytically challenging, especially with unmanned aerial vehicle (UAV) sampling.

Purpose of the Study:

• To present miniaturized, field-deployable methods for halogen speciation in volcanic plumes using UAV platforms.
• To enable selective detection and quantification of molecular halogens and interhalogens.

Main Methods:

• Utilized coated syringe filters (cis-stilbene and 1,3,5-trimethoxybenzene) for in situ derivatization and detection.
• Developed an alkaline trap system ('Bubbler') for total halogen and sulfur quantification.
• Validated methods using a chlorine permeation source in laboratory and dilution chamber experiments.

Main Results:

• Achieved sub-ng detection limits for gas chromatography-high-resolution mass spectrometry (GC-HRMS) based speciation.
• Attained sub-µg detection limits for ion chromatography of total halogens.
• Demonstrated the feasibility of quantitative, UAV-based halogen speciation.

Conclusions:

• The developed methods are suitable for UAV-based sampling of volcanic plumes.
• This research enhances the understanding of volcanic gas chemistry and atmospheric trace gas analysis.
• Offers new possibilities for monitoring volcanic activity and atmospheric processes.