Aquaphotomics Investigation of Flow-Induced Changes in Water Molecular Structure

This pilot study investigates the effects of laminar water flow on the molecular structure of purified water (PW) and mineral water (MW) using Aquaphotomics in the near-infrared first overtone region (1300–1600 nm). A custom temperature-controlled flow cuvette system was developed to enable real-time, non-invasive spectral monitoring while minimizing light-induced perturbations. Spectra were acquired at four flow rates: high (10 cm·s−1), medium (5 cm·s−1), low (2 cm·s−1), and static (0 cm·s−1). Multivariate analyses (PCA, PLSR, SIMCA) and Aquagram visualization revealed that increasing flow rates strongly enhanced hydrogen-bonded water structures in both water types, accompanied by a slight decrease in sample temperature. Mineral water exhibited a more cooperative system-wide spectral response reflecting hydrogen-bond network reorganization and greater thermal stability compared to purified water, attributed to the stabilizing role of dissolved minerals in forming persistent hydration shells and ion hydration structures. These findings demonstrate that flow rate acts as a molecular regulator modulating the cooperativity and stability of water’s hydrogen-bond network. The developed flow-Aquaphotomics approach provides a powerful tool for real-time monitoring of dynamic water systems and offers new insights into flow-dependent processes in biology, medicine, and environmental science.