Group formation and choice of standard substances in the determination of total concentrations of similar compounds as total indices

Resumo

Determination of the total concentration (с_Σ) of similar organic compounds as an total index (TI), expressed in terms of a standard substance of X_st, is a widely used but poorly studied type of chemical analysis. The main problem is the inaccuracy of estimate с_Σ. The article considers reasons for the appearance of systematic errors, rules of formation of groups of simultaneously determined compounds, and the choice of X_st. A classification of TI taking into account the nature of X_st is proposed. To improve the accuracy of analysis, it is expedient to simultaneously use of several standards and construct multivariate calibration dependences.