Spectroscopic Investigation of Chemical Transformations in Complex Aqueous Systems

Abstract

Chemical transformations in natural waters, industrial effluents and biological fluids occur in mixtures containing dissolved salts, organic matter, metal ions, suspended particles and reactive intermediates. Following these changes in real time and without disturbing the sample is a major analytical challenge. This article examines how ultraviolet-visible absorption, infrared, Raman, nuclear magnetic resonance, fluorescence and mass spectrometric methods can be combined to investigate hydrolysis, photodegradation, redox reactions and metal complexation in complex aqueous systems. The strengths and limits of each technique are discussed in relation to water absorption, overlapping signals, low concentrations and matrix effects. Chemometric tools, including multivariate curve resolution and parallel factor analysis, are presented as essential means of separating overlapping spectra and extracting kinetic information. A representative case of dye degradation illustrates how spectral decay can be converted into rate constants and mechanistic insight. The numerical values shown are illustrative and serve to explain the analysis. The article concludes that integrated multi-technique spectroscopy, supported by careful data treatment, provides the most reliable route to understanding aqueous chemical change and supports better water quality monitoring and treatment design.