Microplastic extraction method optimisation in solid marine matrices, to preserve integrity and polymer recovery.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Marine Biology

Background:

• Effective microplastic extraction from marine environments is crucial for mitigation strategies.
• Existing methods often lack comparability and reproducibility due to protocol variations.
• Polymer degradation during extraction hinders accurate microplastic analysis.

Purpose of the Study:

• To optimize an efficient and non-degrading method for microplastic extraction from solid marine matrices.
• To evaluate different digestion solutions and density separation salts for microplastic isolation.
• To validate the optimized protocol on real marine samples and assess microplastic accumulation.

Main Methods:

• Digestion of organic matter using 10% KOH, 15% H2O2, and 35% HNO3.
• Density separation of microplastics using NaCl, ZnCl2, and NaI solutions.
• Raman spectroscopy to monitor polymer integrity during extraction.
• Application of the optimized protocol to sediment and holothurian samples.

Main Results:

• 10% KOH digestion at 60°C for 24h and 30% ZnCl2 density separation were optimal, preserving polymer integrity.
• Holothurians showed higher microplastic abundance in smaller size fractions (1-500 μm, 500-1000 μm).
• Sediment samples contained more microplastics in larger size fractions (500-1000 μm, 1000-1500 μm).
• 95% of recovered microplastics were identified using a Raman spectral database.

Conclusions:

• The optimized protocol provides a robust, polymer-preserving method for microplastic extraction from marine solids.
• This method enhances the reliability of microplastic pollution assessments in coastal ecosystems.
• The findings contribute to standardized microplastic analysis and environmental monitoring.