Co-staining microplastics with Nile Red and Rose Bengal for improved optical quantification

Area of Science:

• Environmental Science
• Analytical Chemistry
• Polymer Science

Background:

• Microplastic (MP) contamination poses a significant environmental threat, necessitating accurate quantification for risk assessment.
• Current MP quantification methods struggle to differentiate plastic from natural organic matter and are time-consuming.
• Incomplete digestion of natural polymers during sample preparation leads to inaccuracies in MP analysis.

Purpose of the Study:

• To develop an innovative optical microscopy technique for accurate microplastic quantification.
• To improve the differentiation between natural and synthetic polymer fragments in environmental samples.
• To reduce errors and save time in microplastic analysis.

Main Methods:

• A sequential co-staining technique using Nile Red (NR) and Rose Bengal (RB) was developed.
• Natural polymers (cellulose, protein, lignin, chitin) and synthetic polymers (PVC, PS, PET, PP, Nylon, HDPE, LDPE) were stained with NR and RB.
• The efficacy of co-staining for distinguishing natural from synthetic fragments was evaluated using optical microscopy.

Main Results:

• Co-staining with Nile Red and Rose Bengal effectively separates natural and synthetic polymer fragments.
• The technique significantly improves the accuracy of visual microplastic identification.
• Simultaneous staining on the same filter reduces counting errors and saves considerable time.

Conclusions:

• The sequential co-staining technique offers a more reliable method for microplastic quantification.
• This approach enhances the accuracy of microplastic analysis in diverse environmental matrices.
• Improved monitoring capabilities will support better-informed risk assessments and mitigation strategies for microplastic pollution.