Extending the Linear Dynamic Range of Single Particle ICP-MS for the Quantification of Microplastics

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastic accumulation poses risks to human health, necessitating advanced analytical methods for detection and characterization.
• Single particle inductively coupled plasma mass spectrometry (spICP-MS) shows promise for microplastic analysis due to its detection capabilities and speed.
• Current spICP-MS methods struggle with accurate sizing and quantification of microplastics, particularly those larger than 3 μm, due to carbon content limitations and transport inefficiencies.

Purpose of the Study:

• To extend the linear dynamic range of spICP-MS for accurate quantification of polystyrene microplastics (PS MPs) up to 5 μm.
• To improve the detection and quantification of microplastic particle number concentration (PNC) using spICP-MS.
• To address limitations in spICP-MS analysis of larger microplastic particles by optimizing sample introduction and operating parameters.

Main Methods:

• Utilized a high-efficiency sample introduction system for spICP-MS.
• Optimized the ¹³C signal and reduced nebulizer gas flow to enhance the transport of larger particles.
• Quantified polystyrene microparticles (PS MPs) ranging from 2 to 5 μm by monitoring their carbon content (¹³C⁺).

Main Results:

• Achieved reliable quantification of particle number concentration (PNC) within 20% of stock concentrations for PS MPs from 2 to 5 μm.
• Demonstrated accurate quantification for PS MPs within mixtures, irrespective of the PNC ratio.
• Extended the accurate quantification range of spICP-MS for PS MPs to larger particle sizes (up to 5 μm).

Conclusions:

• Optimized spICP-MS parameters, including lowered nebulizer gas flow, significantly improve the analysis of larger microplastics.
• The enhanced spICP-MS method provides reliable quantification of microplastic particle number concentration, crucial for environmental and health risk assessments.
• This advancement offers a more robust analytical tool for addressing concerns related to microplastic pollution.