Analytical Methods for Microplastic Detection in Hepatic and Gastrointestinal Human Tissues: A Review and Methodological Framework

Microplastics (MPs) and nanoplastics (NPs) accumulate in human hepatic and gastrointestinal (GI) tissues. However, differences in sampling strategies, tissue preparation, analytical techniques, and quality assurance procedures have resulted in substantial methodological heterogeneity, limiting the comparability and reproducibility of published findings. Therefore, this review aims to critically evaluate current analytical methodologies for the detection and characterization of MPs and NPs in hepatic and GI tissues, highlight methodological strengths, limitations, and emerging technologies, and identify priorities for methodological standardization. Studies demonstrate that no single analytical technique can simultaneously provide comprehensive information on particle size, morphology, polymer composition, spatial localization, and concentration. While Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), and emerging multimodal imaging techniques each offer distinct advantages, reflecting their different underlying detection principles, methodological variability remains a major barrier to cross-study comparison. Human tissue studies are further constrained by limited sample availability, contamination risks, and inconsistent quality assurance procedures. Future progress will depend on harmonized, organ-specific analytical workflows integrating optimized tissue digestion, rigorous contamination control, complementary spectroscopic approaches, and standardized reporting metrics. Establishing unified methodological guidelines is essential to improve reproducibility, facilitate quantitative evidence synthesis, and advance both environmental exposure assessment and clinical research on MPs and NPs in hepatic and gastrointestinal tissues.