Raman probe for the simultaneous measurement of anion concentration in mixtures of salt solutions

We propose to detect by Raman spectrometry the presence of several anions in mixtures of salt solutions and to measure simultaneously their respective concentrations. In this study we show how chemometric methods based on statistical analysis like Principal Components Analysis (PCA) and Partial Least Square Regression (PLSR) can be applied for the spectra treatment. Unlike current water probes often based on conductivity, our new Raman sensor is able to identify simultaneously and in one single measurement several anions such as NO₃^-, SO₄^2-, HPO₄^2- or Cl^- sought for the water pollution monitoring. Moreover our sensor gives rise to reliable, accurate and fast measurement (a few seconds) and can therefore be very useful for in situ water quality control applications.