In the last years, efforts to study and investigate the effects of microplastics (MPs) have greatly increased. To fully understand the impact of MPs, comprehensive characterization is required. Due to the wide range of properties of interest, typically multiple analytical techniques must be applied. Besides established techniques such as FTIR/Raman Spectroscopy useful for the identification of the polymer type of MPs, recently the application of LA-ICP-MS for MPs analysis was proposed. Due to its high sensitivity, LA-ICP-MS can offer insights into the metal content of individual MPs which can provide additional information about the presence or absence of potentially harmful species. Additionally, recent works showed the capabilities of directly detecting MPs based on the 13C+ signal.

In this work, recent results of applying LA-ICP-MS for MPs analysis are presented. Two different approaches for measuring MPs via LA-ICP-MS are presented and their advantages and limitations are discussed. 

Mounting of individual particles in a resin and preparing cross-sections: This approach enables conventional LA-ICP-MS imaging to analyze MPs. To demonstrate its applicaiton, the interaction of MPs (PVC, PE, PS) exposed either to river water or UV radiation with heavy metals (Pb, Cd, Cr) is investiaged. Using matrix-matched standards for each polymer type, quantitative images are obtained.

Direct sampling of individual MPs based on LA-single particle-ICP-MS. With this approach individual MPs particles are non-destructively sampled from a substrate and transported to the ICP-MS. The ICP-MS is operated in single-event mode and each particle is detected as a spike in the transient 13C+ signal. To enable the determination of the particle mass and therefore also the particle size based on the carbon signal, we developed a calibration approach based on the ablation of polymer thin films. With this approach, the size of spherical PS, PVC, and PMMA particles in the low µm range are correctly determined.