Abstract

In this study, monoatomic and thus IR-inactive ions were determined via infrared attenuated total reflection (IR-ATR) spectroscopy including Cl⁻, Na⁺, Mg²⁺, Ca²⁺, K⁺ and Br⁻, next to the IR-active ion SO42-. The determination of IR-inactive ions is enabled, as each ion influences the infrared spectrum of bulk water by organizing the water molecules within the solvation shell around the ionic species in a unique way. Furthermore, the influence of temperature was taken into account for the potential application of this analytical technique in real-world scenarios. Using chemometric data analysis, seven ions could be discriminated at temperatures ranging between 3 ℃ and 45 ℃. Finally, within a sample of seawater, Cl⁻, Na⁺, Mg²⁺ and SO42- could be simultaneously quantified, while the concentrations of Ca²⁺, K⁺ and Br⁻ remained below the achievable limits of detection.

© 2016 The Author(s)

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