X-ray fluorescence spectrometry for the quantification and the mapping of metal(loid)s in animal samples: a review

Abstract

The increasing release of metal(loid)s into ecosystems due to industrial, agricultural, and urban activities raises major concerns for environmental and human health. Understanding how these elements are taken up by organisms, distributed among organs, and stored over time is essential for evaluating exposure, bioaccumulation, and long-term risks. However, conventional analytical methods such as inductively coupled plasma mass spectrometry, rely on destructive sample preparation and laboratory-based workflows, limiting their suitability for rapid screening, spatially resolved analysis, or the preservation of valuable biological material. In this context, the expanding use of X-ray fluorescence reflects the growing demand for non-destructive, multi-elemental approaches applicable to ecotoxicology, biomedical sciences, wildlife monitoring, and forensic investigations. Key scientific challenges remain, notably matrix effects, calibration strategies, and the quantification of trace elements in heterogeneous biological matrices such as soft tissues, hard tissues, and fluids. Recent advances in portable instruments, micro-focused beams, and synchrotron sources have enhanced sensitivity, spatial resolution, and methodological robustness, improving prospects for integrated risk assessment. Here we review three decades of X-ray fluorescence applications in animal samples, including humans, for quantifying and mapping metal(loid)s. The main points are: (1) a synthesis of analytical considerations including sample preparation, matrix effects, detection limits, and calibration, across distinct X-ray fluorescence configurations, describing their respective strengths, limitations, and suitability for biological matrices; (2) identification of trends, knowledge gaps, and methodological developments across studies published from 1994 to 2026, encompassing diverse tissues and fluids, as well as spatially resolved elemental imaging. We show that X-ray fluorescence offers unique opportunities for non-destructive multi-elemental analysis, environmental monitoring, medical and veterinary applications, and forensic authentication, while underlining the need for improved standardisation, calibration, and cross-validation to strengthen its role as a complementary tool to conventional analytical techniques.