Integrated laser ablation and computed tomography: detecting the chemical footprint of microplastics and reconstructing 3D biological tissues

Detecting and characterizing microplastics within biological tissues remains analytically challenging due to their small size, complex composition, and the heterogeneous nature of biological matrices. Existing methods often rely on destructive sample preparation or only provide partial information, highlighting the need for advanced techniques that can simultaneously resolve both the structural and chemical features of microplastics in situ. To address this gap, we introduce a multimodal analytical approach that integrates micro-computed tomography (μCT), which enables non-invasive volumetric imaging of the tissue with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to detect microplastics based on their metal markers. Rat tissue was spiked with polyethylene terephthalate (PET) microplastics, and results showed that μCT imaging alone was insufficient for definitively determining microplastics. However, PET contained several elements, such as antimony and cobalt, and it was possible to detect PET microplastics using LA-ICP-MS based on those metal markers. Furthermore, the developed workflow combining μCT and LA-ICP-MS enabled volumetric segmentation of microplastic reconstruction based on their 3D distribution and evaluation of their size distribution. The results demonstrate that integrating LA-ICP-MS spatial element mapping of PET metal markers facilitates precise validation and segmentation of microplastic locations within tissue on μCT. The proposed protocol was evaluated against a reference size distribution method, addressing the associated detection limitations. Overall, this dual-modality approach provides a proof of concept for microplastic detection in biological tissues by combining both structural and chemical analyses.