CO₂-based matrix-independent carbon quantification approach for single microplastic-ICP-MS analysis

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Accurate size determination of microplastics (MPs) is crucial for environmental monitoring.
• Existing methods for MP size analysis using sp-ICP-MS often suffer from matrix and size-dependent calibration issues.
• There is a need for a robust and independent calibration strategy for reliable MP quantification.

Purpose of the Study:

• To develop and validate a novel carbon dioxide (CO2)-based calibration approach for matrix-independent size determination of microplastic particles.
• To enable accurate size measurements of microplastics in the range of 2 to 7 μm using single particle inductively coupled plasma-mass spectrometry (sp-ICP-MS).
• To overcome the limitations of current calibration methods in microplastic analysis.

Main Methods:

• Implementation of a CO2 gas calibration strategy within the sp-ICP-MS workflow.
• Adjustment of instrument flow rates to optimize particle signal detection.
• Validation of the developed method using Scanning Electron Microscopy (SEM) and analysis of samples in various matrices (river water, saline solutions).

Main Results:

• The CO2-based calibration demonstrated excellent linearity and reproducibility for microplastic size determination.
• Minimal matrix effects were observed across diverse sample types, confirming the matrix-independent nature of the approach.
• Accurate sizing of microplastic particles between 2 and 7 μm was achieved, validated by SEM.

Conclusions:

• The developed CO2-based calibration method provides a robust and accurate solution for microplastic size determination using sp-ICP-MS.
• This approach effectively eliminates matrix- and size-dependent calibration limitations, improving analytical reliability.
• The advancement facilitates more precise environmental monitoring and assessment of plastic pollution.