Innovation spotlight: ExactMP™

One persistent challenge in microplastic research is introducing a known number of particles into a sample. For spike experiments, recovery tests, or interlaboratory comparisons, researchers need materials that allow microplastics to be delivered reliably, transported safely, and preserved without particle loss or contamination.

For a long time, we explored different approaches to solve this problem. The goal was simple in theory but difficult in practice: create a system that allows a precise number of microplastic particles to be embedded in a sample, while also enabling the particles to be counted and characterized beforehand so the exact particle number and size distribution are known.

After many rounds of testing and trial-and-error, we developed ExactMP™.

ExactMP™ uses a pure, water-soluble pullulan film to immobilize microplastic particles in a stable and homogeneous matrix. Because the particles remain fixed within the film, they can be imaged and quantified prior to use, allowing the particle count and size distribution of each

sample to be determined in advance.

When the film is introduced into water, it dissolves completely in less than an hour, releasing the embedded microplastics without leaving interfering residues.

ExactMP™ was designed to support laboratories working on:

• spike experiments

• recovery tests

• method validation

• repeatability assessments

• interlaboratory comparisons

The materials are available in beads, fragments, and fibers, and can be provided in kits of 4, 12, or 24 individual samples depending on experimental needs. Each sample is unique and accompanied by its own dataset describing particle number, estimated mass, and size distribution.

ExactMP™ represents a practical step toward more controlled and reproducible microplastic experiments.