Application of the Algorithm of Doolittle Analysis and Multivariate Calibration to Simultaneous UV-Spectrometric Determination of NO^-₃ and NO^-₂

The Doolittle numerical analytical method together with the multivariate calibration method was applied to the UV-spectrophotometric determination of NO-3 and NO-2,to overcome the difficulty of overlapping of absorption spectra of the 2 anions in the spectral range of 190 nm to 230 nm,which was the cause of impossibility of their direct determination.Data of 1st derivative of the absorbance values of NO-3 and NO-2 were used for data treatment in Doolittle analysis and multivariate calibration.As shown by the experimental results,values of relative deviation of the analytical results obtained by the present method were in the range from -4.56% to 9.02%,which were much more precise than the values of relative deviation in the range from -21.03% to 36.40% as obtained by the P-matrix method.It was shown evidently that the proposed method was superior to be used for dissolution of spectral overlapping.