The analytical quest for sub-micron plastics in biological matrices

•The sub-micron fraction of microplastics dominates on a particle number basis.•The biological fate of sub-micron plastics (SMP) in organisms is poorly understood.•No method is avialable yet for identification and quantifiction of SMP in organisms.•An extraction, concentration, characterisation workflow for SMP in biota is presented .•Metal-doping of polymeric particles may circumvent current analytical limitations. [Display omitted] The current debate on hazards associated with sub-micron sized plastics is hampered by a lack of quantitative data on the uptake and biological fate of plastics in organisms. Analytical methods should be developed to identify, characterize, and quantify sub-micron particulate plastic in biota to understand their biological fate in terms of biodistribution, localization, bioaccumulation and clearance. Here we give a perspective on a promising workflow of sample preparation methods and techniques that could enable analysis of sub-micron plastics in biological matrices and discuss their application for biological fate studies of particulate plastic in organisms. We also expect these methods to be largely transferrable to studies considering sub-micron plastics in food, consumer products, human and some environmental compartments.