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

This study presents a new CO₂-based, matrix-independent calibration approach for size determination of microplastic (MP) particles using single particle inductively coupled plasma-mass spectrometry (sp-ICP-MS). By incorporating a CO₂ gas calibration approach and upon adjusting the flow rates, an accurate size determination of MPs between 2 and 7 μm was enabled. Scanning electron microscopy (SEM) was successfully applied for method validation. The CO₂ gas calibration curves exhibited excellent linearity and reproducibility, with minimal matrix effects across different sample types and matrices, including river water and saline solutions. This CO₂-based approach eliminates the limitations of matrix- and size-dependent calibrations, enabling robust and accurate size determinations of MPs. This advancement represents a significant step forward in the analytical capabilities for MPs, paving the way for improved environmental monitoring and assessment of plastic pollution.