An approach to measure the number concentration and particle size distribution of microplastics using LA-sp-ICP-MS

Abstract

Microplastics (MPs) are one of the major environmental challenges in our current times. To fully understand the impact of MPs on different ecosystem and to develop and employ appropriate regulations it is important to have analytical tools for a comprehensive characterization available. Nowadays, there is a wide range of analytical techniques used for the analysis of MPs each coming with their unique advantages and limitations. Besides conventional techniques such as optical microscopy, FT-IR and Raman spectroscopy also ICP-MS has found its way into the field of MPs. Several papers have been published reporting the use of single particle sp-ICP-MS to directly analyze the number concentration and size distribution in liquid samples. Additionally, a first work by van Acker et al. reported the use of LA-ICP-MS for a direct qualitative detection of individual MPs [1]. In this contribution, we propose a novel approach to prepare standards based on polymer thin films to quantify the size of the individual MPs in the low μm range enabling the investigation of the particle size distribution usingLA-sp-ICP-MS. Additionally, we investigate the transport efficiency (TE) of our LA-sp-ICP-MS method in respect to different measurement parameters, particle sizes and substrates. TE is an important metric in the field of sp-ICP-MS which is typically determined experimentally and directly influences the measurement of the particle number concentration.