Microplastic and Nanoplastic Metrology

Summary

The mission of the Micro and Nanoplastic (MNP) Metrology Project is to assist regulators in assessing the human health and environmental risks associated with plastics degrading in our food, water, and environment, which are currently unknown. Our focus is on the development of validated methods to separate and characterize the micro and nanoplastic (MNP) materials that form though degradation of consumer, commercial and industrial products. Initial development of suitable nanoplastic test materials will ensure accuracy of measurements that can underpin regulatory outcomes for current and future products.

UPDATE June 2022:  See the work MNP Metrology project staff are doing to develop Airborne Microplastic Sampling and Characterization approaches

Description

The Micro and Nanoplastic (MNP) Metrology Project aims to develop a toolbox of methods for size-based separations from complex matrices, chemical characterization protocols, and test materials necessary to enable quantification of micro- and nano-sized plastic particles, a need articulated by our stakeholders for assessing their risk and potential exposure. The project seeks to primarily support the efforts of U.S. regulatory agencies whose mission is to protect human health and the environment. 

The MNP Metrology Project's goal is to develop validated characterization methods to support and enable our stakeholders to perform the necessary human exposure and risk assessments. 

Credit: Marcela Najarro/NIST

In the next three years (FY22-FY24), the MNP Metrology Project will focus on addressing measurement challenges surrounding the development of methods that are necessary for isolating, characterizing, and quantifying MNPs. By combining the development of both size-based separations from complex matrices and suitable test materials, stakeholder needs for chemical characterization protocols across a broad application space can be addressed.

Goal 1:  Develop and disseminate MNP separations and qualitative characterization methods using model systems (ongoing)
To separate and quantify real-world MNPs in complex matrices, metrology development and baseline measurements of well-characterized, homogeneous plastic controls will provide the foundation for evaluating performance in applied systems. To that end, control materials analogous to their real-world counterparts (i.e., similar separation performance) will be developed to ensure method transferability and stakeholder adoption.  Separation methods will be conducted in simple matrices to develop an initial methodology for size-based fractionation and chemical identification/quantification using spectroscopic and spectrometric approaches.   NOTE:  This goal is partially being worked on in collaboration with the EPA and Jennifer Lynch (division 646).

See the work MNP Metrology project staff are doing to develop Airborne Microplastic Sampling and Characterization approaches

Goal 2:  Internally develop and investigate methods for generating test materials (ongoing)
Reproducible, uniform sources of test MNP materials made from specific polymers are essential for successful method development.  Cryomilling has been identified as a promising candidate for preparing test materials in suitable quantities.  However, methods for reproducibly generating MNP test materials in appropriate size regimes are still needed.  

Goal 3: Qualitatively evaluate MNP chemical signatures in controllably aged test materials (2022)
Real-world MNPs are released primarily as degradation products from the bulk through their production, use, recycling and disposal, which can occur through physical or chemical degradation pathways. These processes alter not only their physical dimensions, but also the surface and near surface chemical properties. To begin elucidating these degradation pathways, chemical signatures of MNP test materials will be evaluated as function of size and composition under controlled degradation environments. Identifying and replicating processes that affect MNP signatures are necessary to improve identification measurements and accurate quantification using spectroscopic and spectrometric approaches which will be applied in real world applications.

Goal 4:  Develop and disseminate MNP quantitative chemical characterization methods using test materials and simple matrices ('22/'23)
Details forthcoming.

Goal 5:  Apply MNP separation and characterization methods to test materials and real-world MNPs in increasingly complex matrices ('23/'24)
Details forthcoming.

Post-doctoral Opening

• NRC Postdoctoral Associate opportunities  
  • Separation and quantitative measurement methods for micro- and nanoplastics in complex matrices
  • Micro- and Nanoplastics Chemical Characterization and Quantification Measurement Science
  • Chemical and Physical Metrology for Micro- and Nanoplastics
• NIST associate position

Major Accomplishments

• ·Valsesia, Parot, Ponti, Mehn, Marino, Melillo, Muramoto, Verkouteren, Hackley, Colpo. “Detection, counting and characterization of nanoplastics in marine bioindicators:  a proof of principle study.” 2021 DOI:  https://doi.org/10.1186/s43591-021-00005-z
• Co-organized workshop entitled “JRC-NIST Virtual Workshop on Nanoplastics Research” (2021).
  • Presentation: Pettibone, Gorham “AF4: tools for enabling detection/identification of nanoparticles” (Pettibone)

Additional Technical Details

• Presentation entitled “Metrology for physical and chemical characterization of micro and nanoplastics in complex matrices” (Gorham) NIST Circular Economy Meeting and Program Review 2021