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SciPi 770: Best Practices: Detecting and Quantifying Micro- Nanoplastics (MNP) in Biological Tissues

What techniques/technologies currently exist for chemical and physical identification of micro/nanoplastics, and how does the application of these technologies need to be adapted for biological matrices?

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(8 Answers)

  • Expert 9

    Available techniques include: visual-based detection methods (e.g., Nile Red staining, SEM, fluorescence microscopy), as well as chemical-based detection methods (e.g., laser direct infrared spectroscopy, micro FT-IR,  micro-Raman Spectroscopy, and py-GC-MS. The main issues with the application of such methods to biological tissues relate to the need to eliminate the additional matrix background arising from the higher quantities of biopolymers like lipids etc. This is compounded in some instances by the lower concentrations of MNPs in some biological tissue samples. These issues mean that more sample treatment steps are required to remove matrix.

  • Expert 3

    FTIR: tissue digestion and filter compatibility (e.g., Anodisc) are critical. Raman: bleaching or background correction is needed, due to tissue's autofluorescence. Py-GC/MS: omplete digestion of tissue to avoid matrix effects. TED-GC/MS: requires clean extracts. MALDI-ToF: needs extensive sample preparation and matrix matching. Optical/Electro microscopy: samples should be dry and conductive, and clear. 

  • Expert 4

    Most of the methods have been mentioned before: FT-IR, micro-FT-IR, Raman spectroscopy, NIR (near infrared), pyrolysis GC/MS, TGA-FTIR TGA-MS, SEM-EDX, AFM-IR, flow cytometry, MALDI-TOF-MS.
    Adaptations are needed to resolve the key issues related to biological tissues of masking small particles, clogging filters, interference of the matrix with spectral signals, and generation of additional signals.

  • Expert 2

    There are reported various methods/ technologies for chemical and physical identification of micro/nanoplastics. The ones most known and used are  the spectroscopic analysis (including FTIR, Raman,  NIR, LDIR), mass spectrometry analysis such as Py-GCMS, TD-GC-MS and MALDI-TOF MS, microscopic techniques (optical microscopy, SEM, TEM). Other used techniques that are not as well known are  flow cytometry and nanoparticle tracking analysis. In order for these analysis to be used for biological samples there are several steps that need to be  followed in order to remove organic matter, avoid matrix interference while also preserving the particles structure. The steps that are required are  sample pretreatments (such as enzymatic digestion,  density separation and chemical oxidation), fluorescent labeling, control of the possible contamination due to sample environment or sample preparation and manipulation and the appropriate standardization and qualification.

  • Expert 1

    FTIR and Raman are  identification methods primarily based on physical attributes (size, shape and color).  PyGCMS is a chemical identification method.  For biological samples, mass spec based methods are appropriate.  Besides GCMS, there are LC-MS/MS based methods that can be improved over time.  These methods are complementary to each other and for the development of standard methods, analysis of samples using two or more methods can help validate the data quality.

  • Expert 8

    physical: microscopy, Image J, manual counting, SEM, DLS, aerosol techniques, AAAF
    chemical and physical: staining, fluoresence microscopy, microspectroscopy with FTIR or Raman, 
    chemical: hot needle test, DSC, NMR, py-GCMS

    All of the above are available for tissues, but the trouble is the extraction and cleanup.

  • Expert 6

    NMR, GPC, and DSC are techniques in addition to IR/Raman/py-GC/MS/LDIR techniques. There are enrichment needed to make enough quantity for those technologies to work. 

  • Expert 7

    Current chemical and physical techniques used to identify and characterize MNPs are FT-IR, Raman, Pyr-GC/MS, Thermal desorption GC/MS, SEM/TEM, DLS.

    To use current techniques for MNPs analysis in biological tissues, MNPs in the tissue need to be digested and extracted.

Experts broadly agree on the main techniques for micro/nanoplastics identification, which include:

  • Spectroscopic methods: FTIR, micro-FTIR, Raman spectroscopy, NIR, LDIR
  • Mass spectrometry: Py-GC/MS, TD-GC-MS, MALDI-TOF MS
  • Microscopy techniques: SEM, TEM, fluorescence microscopy, optical microscopy
  • Other methods: NMR, DSC, flow cytometry, nanoparticle tracking analysis

There is consensus that applying these techniques to biological matrices presents significant challenges requiring adaptation. Key issues identified include:

  • Matrix interference from biopolymers like lipids
  • Background signals and autofluorescence from tissues
  • Lower concentrations of micro/nanoplastics in biological samples
  • Filter clogging and particle masking

Experts agree that sample preparation is critical, with most recommending tissue digestion, matrix removal, and contamination control. Several experts (1, 8) emphasized that multiple complementary methods should be used for validation.

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Debate
(4 Comments)

1 vote 1 0 votes
Expert 8
07/31/2025 02:54
Many of the experts pull the discussion back to the challenges of extraction and cleanup.  This is truly a large gap that needs further testing before analytical instruments can be successful. I would also highlight that this question lumps micro and nanoplastics together, but in fact, different methods are needed for different sized particles.
0
Expert 4
07/31/2025 05:54
The overview of techniques is complete in my opinion and can be incorporated in the manuscript.
0
Expert 2
07/31/2025 07:28
 In my opinion, the presentation of techniques is well done and cover a large area, and could be suitable for being added  to the manuscript. 
0
Expert 5
08/01/2025 08:52
The list of measurement instruments that have been used to identify MNP is much longer than those listed in the comments. But, each technique has limitations which, with the long list of techniques, is beyond the scope of this manuscript.
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