ULTRAVIOLET MULTIWAVELENGTH ABSORPTIOMETRY (UVMA) FOR THE EXAMINATION OF NATURAL-WATERS AND WASTEWATERS .2. DETERMINATION OF NITRATE

A new method for nitrate determination in natural waters and wastewaters based on ultraviolet multiwavelength absorptiometry (UVMA) is proposed. After acquisition of spectral data for a sample, without added reagent or pretreatment at 1 nanometer intervals between 205 and 250 nm, a computational procedure gives in a few seconds the concentration of nitrate. The principle is to use a polynomial correction function to cancel numerically the interferences from suspended and organic matters, and to resolve the system formed by the sum of the proper absorbance of nitrate and the previous function. Matrix calculation is made with the least squares method, which minimizes the error between the measured absorbances and the model. The characteristics of the UVMA method and the residual interferences have been evaluated and a comparison with reference methods for different samples has shown that nitrate UVMA is a valuable tool for fast determination and/or continuous monitoring. © 1990 Springer-Verlag.