What Goes Around Should Not Move Around: Immobilizing Microplastics as a New Approach for Analytical Ring Trials

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastics are pervasive environmental pollutants requiring precise quantification.
• Interlaboratory comparisons (ILCs) are essential for assessing analytical method performance.
• Current parallel ILC designs suffer from high variability due to difficulties in producing identical subsamples.

Purpose of the Study:

• To develop a novel method for preparing microplastic samples for interlaboratory comparisons.
• To enable serial ILC designs for more accurate uncertainty assessment.
• To reduce variability and improve the reliability of microplastic quantification.

Main Methods:

• A filtration-immobilization technique was developed for microplastic particles ≤100 μm.
• Microplastics were permanently immobilized on silicon filters with 10 μm pores.
• A serial ILC design was implemented using the immobilized samples.

Main Results:

• The filtration-immobilization approach successfully created permanently immobilized microplastic samples.
• Serial ILCs using immobilized samples resulted in 77% lower specific measurement uncertainty compared to parallel ILCs.
• Relative standard deviations were reduced from 23% in parallel ILCs to 5% in serial ILCs.

Conclusions:

• The filtration-immobilization method significantly enhances the accuracy and reliability of microplastic quantification in ILCs.
• This approach minimizes uncertainty sources inherent in traditional parallel ILC designs.
• The technique offers potential for sample archiving and creating durable reference materials for particulate matter research.