MODERN ANALYTICAL TECHNIQUES FOR CHEMICAL CHARACTERIZATION OF ENVIRONMENTAL AND PHARMACEUTICAL SAMPLES: A STATE-OF-THE-ART REVIEW

Abstract

The reliable characterisation of environmental and pharmaceutical samples containing chemically diverse substances at trace and ultra-trace levels requires the use of modern analytical techniques. This review covers the main methods for sampling, sample preparation, separation, detection, characterisation, and data processing of contaminants, active pharmaceutical ingredients, impurities, degradation products, metabolites, toxic elements, microplastics and emerging pollutants. Complex mixtures can be effectively resolved using chromatographic methods such as HPLC, UHPLC, gas chromatography, hydrophilic interaction chromatography, multidimensional separations, and supercritical fluid chromatography. They can be coupled with tandem and high-resolution mass spectrometry to enable targeted, suspect screening, non-target and structural elucidation. The UV-visible, fluorescence, FTIR, NIR, Raman, SERS, NMR, ICP-MS, AAS, DSC, TGA, SEM, TEM, XRD, XPS and AFM techniques provide a range of information on molecular and structural composition and characterisation, elemental, thermal, morphological and surface characterisation, respectively. Portable and on-site analysis is improved with electrochemical sensors, biosensors and miniaturised systems. Other interesting topics presented in the review include matrix effects, sample stability, validation needs for analytical methods, chemometric modelling, machine learning, green analytical chemistry and regulatory aspects. Further developments are likely to be directed towards automation, portability, AI, digital twins, real-time monitoring and harmonised analytical standards to achieve more sustainable, sensitive and reliable chemical analysis.