Selective determination of mercury (II) ion in water by near-infrared diffuse reflection spectroscopy with the aid of preconcentration and multivariate calibration

A method for the selective determination of mercury (II) ion in water was developed by using preconcentration and near-infrared diffuse reflection spectroscopy (NIRDRS). For the method, thiol-functionalized silica porous particles (TFSPP) were prepared for adsorption of mercury (II) ion from dilute solutions. The adsorbent proved very efficient for the adsorption of the analyte, and NIRDRS combined with partial least squares (PLS) for calibration modeling was found suitable for a fast analysis. Under optimized conditions, the adsorption rate of the analyte can be above 98% within 5 min. Synthetic samples prepared with river water and interferences were used for method development. The results show a correlation coefficient of R = 0.9667 between reference values and prediction results for the analyte, and the recovery rates were in the range of 81.5-122% for the validation samples in the concentration range of 3.3-26.9 mg L−1.