Direct Characterization of Halogen-Based Microplastics via Single-Event ICP-Mass Spectrometry in Negative-Ion Mode

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Halogen-containing microplastics, including polytetrafluoroethylene (PTFE) and poly(vinyl chloride) (PVC), are significant environmental contaminants.
• Selective characterization of these microplastics using traditional ICP-MS is difficult, especially for fluoropolymers, due to limitations in detecting fluorine ions.

Purpose of the Study:

• To develop a direct method for particle-resolved characterization of halogen-containing microplastics using negative-ion ICP-MS.
• To establish a selective detection strategy for fluorine and chlorine in microplastics without relying on indirect methods.

Main Methods:

• Utilized negative-ion single-event ICP-MS for direct monitoring of F- and Cl- ions from PTFE and PVC particle standards.
• Employed scanning electron microscopy (SEM) for particle morphology and size analysis.
• Optimized acquisition and instrumental conditions for reliable transient event detection.

Main Results:

• Achieved reliable transient detection of F- and Cl- at a dwell time of 100 μs.
• Established size detection limits of 1.18 μm (PTFE) and 0.73 μm (PVC) with conventional systems, improving to 0.68 μm (PTFE) and 0.45 μm (PVC) with high-efficiency systems.
• Assessed quantification strategies including external calibration and transport-efficiency-based workflows for negative-mode operation.

Conclusions:

• Negative-ion single-event ICP-MS provides a direct and effective platform for fluorine- and chlorine-selective microplastic detection and sizing.
• This technique expands the analytical capabilities for microplastic analysis, overcoming limitations of previous indirect fluorine detection or carbon-based methods.