Quick and efficient microplastic isolation from fatty fish tissues by surfactant-enhanced alkaline digestion

For monitoring microplastic contamination in fish tissues, tissue digestion into filterable components prior to microplastic identification and quantification should be quick and efficient, providing satisfying microplastic recoveries of relevant particle sizes. Filtration with a small pore size, necessary to target small particles, is a challenge. Some proposed protocols take several days. To improve this, a combination of surfactants (Tween (R)-20 and Triton (TM) X-100) with potassium hydroxide (KOH) and pH neutralization was used. Fish bones were removed in tissue preparation prior to digestion. Recovery down to ca. 60-80 mu m worked well for PA-66, PE, PET, PP, PS and PVC. In conclusion, we developed a comparatively swift digestion protocol, enabling filtration of 100 g samples with a pore size of 10 mu m, for fish fillets with high (mackerel), intermediate (salmon, plaice) and low (cod) fat contents, fish liver, head kidney and oil samples, within 16-24 h.

Automated summary

In order to monitor microplastic contamination in fish tissues efficiently, a swift digestion protocol using a combination of surfactants and potassium hydroxide was developed. This protocol allowed for quick digestion of the tissues into filterable components, enabling identification and quantification of microplastics. The method achieved satisfactory recovery of microplastics of different particle sizes.