Determination of nitrate and other water quality parameters in groundwaterfrom UV/Vis spectra employing partial least squares regression

The use of UV/Vis spectroscopy in combination with partial least squares (P LS) regression for the simultaneous prediction of nitrate and non-purgeable organic carbon (NPOC) in groundwaters was evaluated. A model of high quali ty was obtained using first order derivative spectra in the range 200-300 n m. Inclusion of non-UV-absorbing constituents in the modeling procedure, i. e.. chloride, sulfate, fluoride, total carbon (TC), inorganic carbon (IC), alkalinity, pH and conductivity was also evaluated. This model seemed to be useful for prediction of chloride, TC, IC, alkalinity and conductivity, wh ile its ability to predict sulfate, fluoride and pH was poor. In conclusion , application of PLS regression, which requires neither filtration of sampl es nor addition of chemicals, is a promising alternative for fast interpret ation of geochemical patterns of groundwater quality. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.