Automatization of multistep sample preparation for microplastics monitoring in aquatic environments

Abstract Microplastics (MP) have been found in every environmental compartment in urban and remote areas. Although their ubiquity is widely recognized, the lack of harmonized protocols for sampling, sample preparation, and particle identification/quantification hinders comparability among studies. Due to the complex particulate matrix of environmental samples, multiple labor‐intensive treatments are typically required to remove interfering materials prior to the identification of plastic polymers. To reduce workload and improve process repeatability, this paper introduces a novel device that automates the multistage sample preparation of water samples. The performance of the automatic sample preparation device (MAP‐100) was evaluated based on recovery rate, sample contamination, and removal efficiency of the sample matrix. For performance testing, three types of surface water samples (brackish, freshwater, and river) were collected. Results showed recovery rates of 97–99% for test MP sized 355–425 μ m and 100% for those sized 3–4 mm. Low standard deviations (≤ 5%) of recovery rates indicated consistent sample preparation and highly repeatable measurements. No contamination was detected during sample processing. The method, incorporating two hydrogen peroxide treatments, three sequential density separations, and final filtration, effectively removed the sample matrix. Fourier Transform Infrared analysis revealed polyethylene and polypropylene as the most abundant types of plastics in three types of surface waters. Overall, performance tests demonstrated that MAP‐100 is a robust tool for monitoring MP (> 300 μ m) in surface waters.