NIR fiber-optic method with multivariate calibration analysis for determination of inorganic compounds in aqueous solutions

Near-infrared spectra of aqueous solutions were collected by using evanesce nt-field fiber-optic sensors. The spectra of two- and four-electrolyte solu tions were analyzed with a partial least-squares (PLS) algorithm to quantif y the measurements. Our results indicate that the electrolytes can be ident ified and simultaneously determined by using the PLS calibration model. Ele ctrolytes in opaque aqueous mixtures were also studied, and the results are compared with results from clear aqueous solutions.