Pitfalls and Limitations in Microplastic Analyses

A Peristaltic Pump and Filter-Based Method for Aqueous Microplastic Sampling and Analysis

“…Several sample collection procedures for microplastics in marine and freshwater environments have been presented in the existing literature (e.g., refs , , and ). Net sampling and grab sampling are the most common microplastic sampling methods.…”

“…Net sampling involves sampling the water surface using a neuston, bongo, or other types of plankton nets with a flow meter to determine the sample volume. The mesh is typically composed of nylon with a mesh size of 300 μm, although some nets use a smaller mesh size (e.g., <100 μm). ,, The net is typically designed to sample the top 0.5 m of water while it is pulled behind a boat or held by individuals at the water surface . After sample collection, the net is rinsed in a sample container and the material is stored until laboratory analysis.…”

“…After freshwater sampling, the filtered material is brought back to the laboratory to isolate microplastic particles. This is typically conducted through a series of isolation and digestion steps. ,,− Isolating microplastics from particulate matter is typically conducted using a dense (1.2 to 1.8 g/cm 3 ) liquid (e.g., NaCl, ZnCl 2 , and CaCl 2 ) that allows the plastic particles to float and the denser particulates to sink. ,,,,, Care must be taken to choose a solution with an appropriate density for the plastics of interest . For freshwater samples, an organic material is typically digested using an oxidizer and acid, base, and/or enzymatic digestion.…”

“…For freshwater samples, an organic material is typically digested using an oxidizer and acid, base, and/or enzymatic digestion. These chemicals can dissolve or alter microplastics, and therefore they must be used with caution . The microplastic isolation process may require multiple cycles of a given matrix-removal step or other separation processes …”

“…These chemicals can dissolve or alter microplastics, and therefore they must be used with caution. 11 The microplastic isolation process may require multiple cycles of a given matrix-removal step or other separation processes. 29 The size, shape, and polymer type of the microplastics can be determined once they are isolated from the sample matrix.…”