Faster tests reveal six fluoropolymer microplastics, including four rarely tracked types

In recent scientific developments, researchers have made significant strides in identifying and measuring microfluoroplastics (MFPs)—a relatively unexplored category of microplastics that contain fluoropolymer compounds. These materials, which intersect the realms of microplastics and per- and polyfluoroalkyl substances (PFAS), have long been overlooked despite their potential environmental impact. A newly developed testing methodology has now enabled scientists to detect six distinct types of fluoropolymer microplastics, four of which had previously gone unnoticed in environmental studies. This breakthrough comes after a collaborative effort involving researchers from Nankai University and the technical department of Agilent China, whose work has been published in *Environmental Science & Technology*.

The study focused on extracting and quantifying MFPs from various environmental samples such as dust, suspended particulate matter, and sediments. The findings revealed that MFPs accounted for approximately 2% to 8% of the total microplastics identified in these samples. This discovery highlights the presence of fluoropolymer-based microplastics in the environment, which had not been adequately addressed in prior research. Chu Peng, a lead researcher from Nankai University, noted that initial investigations into MFPs were limited due to the lack of reference spectra beyond polytetrafluoroethylene (PTFE), prompting the team to develop a comprehensive database of fluoropolymer reference spectra.

To build this reference library, the researchers employed Agilent’s laser direct infrared (LDIR) spectroscopy technique, a novel approach in microplastics analysis. Unlike traditional Fourier transform infrared (FTIR) spectroscopy, which scans a broad range of wavelengths, LDIR focuses on a narrower band (900–1800 cm⁻¹), where the characteristic C–F bonds of fluoropolymers are located. This makes LDIR particularly effective for detecting MFPs. The team prepared six types of fluoropolymers—PTFE, polyvinylidene fluoride (PVDF), PVDF-hexafluoropropylene copolymer (PVDF-HFP), polytrifluorochloroethylene (PCTFE), ethylene chlorotrifluoroethylene (ECTFE), and fluorinated ethylene propylene (FEP)—in various granule sizes and fiber lengths. Additionally, they created chemically aged versions of these materials to simulate environmental degradation processes.

Sample preparation played a crucial role in the detection process. To ensure accurate identification, microplastics needed to be sufficiently exposed to the spectrometer's light. Traditionally, researchers use mild chemical digestion techniques to remove organic matter without damaging the microplastics. However, given the robust nature of MFPs, the team devised a more aggressive procedure involving exposure to strong acids, bases, and organic solvents. This method significantly increased the number of detectable MFPs by up to 67% to 100%, according to the study. While this harsh digestion might not be suitable for all types of microplastics, it proved highly effective for MFPs, allowing for a more complete analysis of environmental samples.

Experts outside the study praised the adaptability of the new method. Rainer Lohmann, an environmental scientist at the University of Rhode Island, emphasized that while conventional digestion methods remain necessary for certain analyses, the new protocol provides additional insights. Similarly, Rolf Halden, an environmental health engineer at Arizona State University, commended the researchers for preparing and analyzing aged MFPs, noting that the spectral differences between new and weathered samples were clearly defined. Furthermore, variations in particle size or shape did not influence the resulting spectra, reinforcing the reliability of the method.

The practical application of the new technique was demonstrated through experiments involving nonstick cookware. Researchers analyzed microplastics generated during the frying of eggs using nonstick pans coated with PTFE. The results showed that the process released between 3,890 and 6,760 PTFE microplastic particles, underscoring the everyday contribution of household items to the accumulation of MFPs in the environment. As further research unfolds, scientists anticipate that this improved detection method will facilitate a broader understanding of the distribution, behavior, and ecological impact of fluoropolymer microplastics.