Are there methods that can utilize the small sample quantities most typically available and provide confirmational analysis (DSC, NMR, etc)?

Answer Explanations

• No

  Expert 9
  My experience is with non-biological tissues where sample quantities are higher and/or matrix effects are lower, and thus FT-IR for example is appropriate for confirmational analysis - i.e. spectral matching to identify MNPs as specific polymers, with associated (un)certainty.
• Yes

  Expert 3
  DSC can confirm polymer identity via thermal fingerprint, requiring 0.5–5 mg, but micro-DSC variants can use <1 mg. It may be useful identifying polymer blends. NMR can be used for identifying co-polymers or oxidized plastics and requires, typically, >1 mg, but microcoil NMR can work with <100 µg.
• Yes

  Expert 4
  DSC and NMR are indeed suited options also considering the quantities typically available. In addition, FT-IR and RAMAN spectroscopy might be useful, as well as Mass Spectrometry (MALDI-TOF, ESI-MS) and Thermogravimetric Analysis. In some cases, XPS migth be of added value.
• Yes

  Expert 2
   There are several analytical methods that  could provide confirmatory or complementary analysis using  small sample quantities commonly available in microplastic and nanoplastic studies. These techniques could be effective at the microgram to low milligram scale, making them suited for the studies of limited biological or environmental samples. However, each method has  strict limitations regarding the  information that they could  provide with such small quantities, like  chemical structure, crystallinity, thermal properties, or molecular weight. 
• Yes

  Expert 1
  Mass spectrometric methods.  
  While pyrolysis GCMS is becoming popular in MNP analysis, a few studies analyzing biological samples utilized alternative mass spectrometric methods using LC-MS/MS, which is more confirmatory (see Zhang et al., 2021, Environ. Sci. Technol. Letters, 8, 989-994).  Polymers can be depolymerized to produce monomers and those monomers can be analyzed using LC-MS/MS.  In this case, monomers analyzed before and after depolymerization can be subtracted to yield plastic type in the units of mass of a specific plastic.  
• Yes

  Expert 8
  DSC can be used as a confirmational method. Limits of detection for DSC are published for very small microplastics (Lynch et al. 2024 https://doi.org/10.1016/j.envpol.2024.123607
• Yes

  Expert 6
  There is nano DSC technique available. For NMR, which is most confirmational technique, small sample quantities are challenging. 
• Yes

  Expert 7
  Some methods are quite sensitive and small sample quantities are enough, Pyr-GC/MS for example.