Simultaneous Determination of Monoatomic Ions via Infrared Attenuated Total Reflection Spectroscopy in Aqueous Solution at Different Temperatures

摘要

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.