Is there a statistical or otherwise quantitatively meaningful minimum number of particles that each methodology can reliably detect?

Answer Explanations

• Yes (please explain)

  Expert 3
  There is published literature on this. Roughly, it could summarized as such:
  Visual microscopy: 10–50 particles/sample
  uFTIR: 1–10 particles/sample
  uRaman: 1 particle/sample
  py-GC/MS:10–100 ng polymer (10-50 if TED-GC/MS).
• No

  Expert 9
  While inherently even a single MNP can be detected, I agree with the MDA calculation algorithms cited, which show that the minimum reportable number must be 3 to account for sample contamination. In practice, this will be far more and I would say that a figure of around 50 MNPs per sample is the minimum reportable quantity.
• No

  Expert 2
   While single-particle sensitivity is possible in some cases, most methods demand at least hundreds to thousands of detected particles for results to be considered quantitatively meaningful.  Some techniques such as electron microscopy or single-molecule qPCR, can in principle detect individual particles or molecules, but these detections are not usually quantitative.  Other methods like nanoparticle tracking analysis or flow cytometry, usually require concentrations on the order of 10⁶–10⁸ particles per milliliter to generate stable signals.  ICP-MS can detect tens to hundreds of particles per milliliter when elemental composition is favorable but a reliable quantification does not just depend on the instrument’s physical sensitivity but also on statistical confidence.
• Yes (please explain)

  Expert 4
  Such a number of plastic particles needs to be established on a case by case basis and will depend on the tissue, the method of digestion and visualizing the plastics, the plastic properties and the diversity of the particles detected in terms of their composition, size, shape, colour, etc.. 
• No

  Expert 1
  Reproducibility of data is more important.  While detection limit can vary depending on the analytical methodology and sample type, sample preparation can be optimized to achieve analysis within little uncertainty.  This is especially important for biological samples.  Although manuscript states the need to achieve 100 particles (subsection on line 371), this recommendation not scientifically based.  Many human tissue  analysis detected <10 particles (e.g., placenta study from Italy) and achieving 100 particles (e.g., in placenta, brain) can be impossible.   Instead, focus on reproducibility of data, appropriate sample preparation methods to enrich MNPs in extracts and instrumental methods that yield reliable data.
  
  
  
• Yes (please explain)

  Expert 5
  Yes. The answer lies with the statistical design of the experiment which will stipulate adequate methodology to reach a reasonable answer to the research question.
  
  As mentioned earlier, total mass of particles, particle is relevant in Py-GC/MS measurements.
• No

  Expert 8
  Below limit of detection is a perfectly meaningful value.
• Yes (please explain)

  Expert 6
  It is not my expertise area. I think there should be way to do so.