METHODS AND OBJECTS OF CHEMICAL ANALYSIS ISSN title: "Metody i obʺekty himičeskogo analiza" An international journal devoted to all aspects of Analytical chemistry ISSN 2413-6166 (Online), ISSN 1991-0290 (Print)
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The deviations from additivity of absorbtion (DA), connected with the interaction of sample components, lead to systematic errors of analysis. It is necessary to take DA into account when new spectrophotometric methods are developed. Three modes of DA exposure are elaborated to distinguish the statistically significant deviations from the accidental errors. The statistical model calculation is most informative mode, which allows deviations forecasting and the interactive components detecting. As an example, the necessity of DA investigation is demonstrated for total antioxidant determination.

Key words: spectrophotometric analysis, additivity of absorbtion, deviations from additivity, systematic errors of analysis, modes of deviations exposure.