Advancing microplastic characterization in environmental samples using optical photothermal infrared (O-PTIR)...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microplastics are pervasive environmental contaminants with significant ecological and health implications.
• Standardized methods for microplastic detection and identification are lacking, hindering cross-study comparisons.
• Existing techniques like spectroscopy and microscopy have limitations in sensitivity, specificity, and ease of use.

Purpose of the Study:

• To explore and refine Optical Photothermal Infrared (O-PTIR) spectroscopy workflows for enhanced microplastic identification.
• To optimize O-PTIR operational parameters for complex environmental samples, addressing challenges like thermal damage.
• To evaluate O-PTIR's performance against conventional methods for microplastic analysis.

Main Methods:

• Investigated the impact of Nile Red dye pretreatment on microplastic spectral analysis.
• Benchmarked detector configurations and defined optimal laser power thresholds for O-PTIR.
• Assessed cryogenic cooling as a strategy to mitigate laser-induced thermal damage during analysis.

Main Results:

• Nile Red staining altered spectral intensities but preserved diagnostic functional group information.
• Cryogenic cooling effectively reduced thermal damage, with optimized laser power crucial for data quality.
• O-PTIR showed high spectral agreement with ATR-FTIR, offering superior non-contact analysis for irregular microparticles.

Conclusions:

• Optimized O-PTIR workflows provide practical solutions for minimizing thermal damage and retaining spectral integrity.
• O-PTIR is a powerful, non-contact technique for identifying microplastics in complex environmental matrices.
• This study advances microplastic analysis, supporting improved data quality and a better understanding of microplastic behavior.