Main Inorganic Component Measurement of Seawater Using Near-Infrared Spectroscopy

Abstract

The potential of near-infrared (NIR) spectroscopy to measure the main inorganic components of seawater as salt-manufacturing materials was investigated. A total of 72 seawater samples collected from six locations was used, and spectra (1100–1800 nm) were acquired by a NIR spectrophotometer with a 1-mm path length. Principal component analysis (PCA), canonical correlation analysis (CCA), and partial least-squares (PLS) regression were performed based on the reference inorganic components. As a result, the principal component analysis and canonical correlation analysis showed that the near-infrared spectra could be related to the inorganic components of seawater. The partial least-squares regression analysis showed that the inorganic components (ion concentration of Cl⁻, Na⁺, K⁺, SO₄²⁻, and Ca²⁺) could be predicted with good accuracy using NIR spectra and their second derivatives. For Cl⁻ ion and K⁺ ion concentrations, the accuracy was high.