Extending the Linear Dynamic Range of Single Particle ICP-MS for the Quantification of Microplastics

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Abstract

In response to the growing concern of microplastics (1 µm to 5 mm) accumulation in the environment, the development of analytical methods continues to be critical for the detection and characterization of microplastic particles. In this context, an exceptional particle detection capability (down to truly environmentally relevant levels), rapid analysis times, and high sample throughput make single particle inductively coupled plasma mass spectrometry (spICP-MS) very attractive for mi-croplastics analysis. Existing spICP-MS based studies have routinely shown limitations for the accurate sizing and quantifi-cation of particle number concentration through targeting carbon content, with reported size limits of detection between 0.62 µm - 1.6 µm and a substantial reduction in the transport of particles larger than 3 µm. In this work, the linear dynamic range of spICP-MS for the accurate quantification of polystyrene microspheres (PS MPs) via the monitoring of their carbon content (13C+) is extended to larger particle sizes (5 µm) by using a single cell sample introduction system, rigorous optimiza-tion of the 13C signal, and operating at a lowered nebulizer gas flow to improve sample transport of larger particles to the plasma. Reliable quantification of particle number concentration (PNC), accepted as falling within 20 % of expected parti-cle stock concentrations, was achieved through a 20 % lowered nebulizer gas flow for a full suite of commercial PS MPs ranging from 2 µm to 5.0 µm as well as a 2.2 µm and 4.8 µm PS MP contained within mixtures of both materials, regardless of the PNC ratio.

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Keywords

Standards, Nanotechnology, Materials and Environment

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