Application and Validation of the First Automatic Pretreatment Unit for Aquatic Microplastics

Microplastic contamination in aquatic ecosystems is a growing global concern, yet microplastic analysis remains constrained by labor-intensive pretreatment and inconsistency across operators and laboratories. Here, we report the application and validation of the first automatic microplastic pretreatment unit, Shimadzu's MAP-100, designed to standardize this critical step. The unit was evaluated using river water spiked with aged standard microplastics for controlled testing and field-collected seawater for real-sample validation. After automatic pretreatment, Fourier transform infrared (FT-IR) spectral integrity was preserved, enabling reliable polymer identification and recovery rate determination. Detection of soluble organic matter demonstrated effective organic matter removal. Mineral particles were completely eliminated, with zero residual mineral detection. The MAP-100 achieved a higher recovery of aged microplastics (95.6 ± 2.5%) than manual pretreatment (92.7 ± 3.0%), with the greatest improvement observed for small (≤1 mm) and high-density particles. In seawater samples, overall performance remained robust; however, foam microplastics showed reduced recovery due to the overflow tube's narrow diameter and sharp curvature, indicating a need for structural refinement. Despite this limitation, the closed-loop automatic workflow substantially reduces labor and processing time while improving reproducibility and operational safety for standardized microplastic monitoring.