Analyzing microplastics with Nile Red: Emerging trends, challenges, and prospects

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastic pollution is a growing global concern, necessitating reliable detection methods.
• Nile Red (NR) staining has emerged as a popular technique for microplastic analysis due to its simplicity and low cost.
• Existing research highlights the need for a comprehensive review of NR staining protocols and their applications.

Purpose of the Study:

• To review current protocols for microplastic identification using Nile Red staining.
• To analyze the effectiveness and limitations of NR staining based on 56 field observations.
• To identify challenges and propose recommendations for standardizing NR-based microplastic analysis.

Main Methods:

• Literature review of 56 field studies on microplastic pollution and NR staining.
• Analysis of protocols for sample preparation, staining, fluorescence conditions, and data interpretation.
• Evaluation of contamination control measures and validation techniques.

Main Results:

• Nile Red staining is a viable method for visual identification of microplastics (≥ 3 µm - ≤ 5 mm).
• Methodological discrepancies exist, impacting the standardization of NR staining protocols.
• Fluorescence with NR does not exclusively confirm microplastics, requiring further validation.

Conclusions:

• Nile Red staining is a valuable tool for microplastic research, offering a low-cost alternative for initial identification.
• Standardization of sample preparation, staining, and analysis is crucial for reliable and comparable results.
• Complementary techniques, such as spectroscopy, are recommended for definitive chemical identification of NR-stained particles.