Selection of microplastics by Nile Red staining increases environmental sample throughput by micro-Raman spectroscopy

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastic detection requires methods for both identification and quantification.
• Nile Red staining offers cost-effective, high-throughput visualization but lacks chemical specificity.
• Micro-spectroscopy provides chemical characterization but is slow and expensive.

Purpose of the Study:

• To combine Nile Red staining with micro-Raman spectroscopy for enhanced microplastic identification.
• To leverage Nile Red's properties for pre-selection and targeting in micro-Raman analysis.
• To improve the efficiency and throughput of microplastic analysis.

Main Methods:

• Utilizing Nile Red staining for initial particle visualization and quantification.
• Employing micro-Raman spectroscopy for chemical characterization of pre-selected particles.
• Optimizing micro-Raman analysis using a 442 nm laser and orange filter to detect Nile Red luminescence.

Main Results:

• Nile Red staining effectively pre-selects particles for micro-Raman spectroscopy with minimal interference.
• The 442 nm laser induces Nile Red luminescence, enabling targeted micro-Raman analysis.
• Coupling these methods significantly reduces the number of particles requiring identification, improving sample throughput.

Conclusions:

• The combined Nile Red and micro-Raman spectroscopy approach enhances microplastic identification efficiency.
• This integrated method offers a faster, more targeted analysis for microplastics.
• The strategy improves time efficiency for microplastic analysis using micro-Raman spectroscopy.