Спектрофотометрический анализ катализаторов с применением хемометрического алгоритма PLS

Abstract

Introduction. Many transition metals that make up catalysts are capable of forming colored complexes, and spectrophotometry could be a convenient and inexpensive method to estimate their content. However, such techniques are not widely applied in the analysis of catalysts because of the strong overlapping spectra. Multi wave analysis in combination with the chemometric treatment of the spectra can extend the capabilities of the spectrophotometry. The purpose of the experiment reported here was to show the possibility of applying spectrophotometry in combination with the partial least-squares method ( PLS ) to determine metals in catalysts by reactions of complex formations. It was proposed to use a non-selective reagent 4 (2 pyridylazo) resorcinol ( PAR ). Experimental Procedures . Catalysts and dry model mixtures containing one or more metals were decomposed by acids. Spectra of the resulting solutions and spectra of the solutions after adding the above mentioned PAR reagent were recorded. The resulting solutions were also analyzed using the reference method of atomic emission spectroscopy (AES). Results. The possibility to separately determine from 1 to 4 metals by spectrophotometry both on their own absorption in the UV region and using PAR reagent was shown. In the case of determination of several metals the partial least-squares method (PLS) was utilize d for processing the spectral information. To construct the PLS-calibration for the first time, the absorption spectra of the real samples of catalysts in combination with data obtained by atomic emission spectroscopy method (AES) was used. This approach allowed considering the influence of the matrix and quantifying metals in catalysts with errors of 1−5%, and with the relative standard deviation of 0.01 to 0.06, which is comparable in accuracy to the AES method. Key words: spectrophotometric analysis, the partial least-squares method, catalysts. (Russian) DOI: http://dx.doi.org/10.15826/analitika.2015.19.4.004 T.Iu. Zheleznova 1 , I.V. Vlasova 1 , A.V. Shilova 2 Omsk State University named after F.M. Dostoevskii(OmSU), Omsk, Russian Federation Institute of Hydrocarbon Processing , Siberian Branch of the Russian Academy of Sciences (IHcP, SB RAS), Omsk , Russian Federation