Table 1.

Overview of characterization modes. Application towards MPLs and/or NPLs, sample preparation type, and tradeoffs are summarized (Part 1 of 2).

Method	Category	Particle Size Regime	Sample Preparation	Advantages	Disadvantages
FTIR	Identification	MPLs	Dry	Adequate resolution and well-reported method. Identifies polymers, additives, and adsorbents. Spectral libraries available. Resolution: ~10 µm [32]	Sensitive to confounding chemical noise from additives/adsorbents.
Raman	Identification/Quantification	MPLs/NPLs	Dry (Wet: Raman Tweezers)	Higher spatial resolution, well-reported method. Identifies polymers, additives, and adsorbents. Spectral libraries available. Resolution: ~1 nm [39]	Sensitive to confounding chemical noise from additives/adsorbents. Fluorescence from the material can be an issue.
H-NMR	Identification	MPLs	Wet	Possible confirmatory technique for structural analysis. Identifies the structure of oxidized species. LOD: 1 µg/mL/6 µg [46,47,48]	Extensive sample preparation.
Pyrolysis	Identification/Quantification	MPLs/NPLs	Wet	LoD is low for the concentration and size of particles. Great application for biological samples. LOD: 1.6/2.31 µg/g [29,50]	Sample destruction. Extensive sample preparation.
FFF-MALS	Identification/Quantification	MPLs/NPLs	Wet	Various size regimes can be studied based on applied mode (field/pore shape nature and size 0.38 µg/g) [50].	Not well studied. Largely proprietary.
Counting/Weighing	Quantification	MPLs (counting)/MPLs and NPL weighing	Dry	Mainly benefits larger MPLs and mesoplastics.	NPL and lower MPL regime more challenging to weigh/count.