Recently, near-IR spectroscopic measurements of electrolytes in aqueous solutions have been explored. The basis for this technique is the perturbations of electrolytes on the near-IR water bands. Both measurements of a single electrolyte and simultaneous measurements of several electrolytes have been investigated. Determination of seawater salinity is also possible. Most of these measurements were made in the near-IR region from 1100 to 2500 nm. In contrast, the short-wavelength near-IR region from 700 to 1200 nm has received much less attention.
Jie Lin and Chris W. Brown, "Spectroscopic Measurement of NaCl and Seawater Salinity in the Near-IR Region of 680–1230 nm," Appl. Spectrosc. 47, 239-241 (1993)