Comparative characterization of different variants of quantitative chromatographic analysis using external and internal standards

Chromatographic analysis of a series of two-component samples (solutions of a target analyte and a standard) allows simultaneous comparison of the possibilities and features of six variants of quantitative analysis using the external and internal standards techniques according to the criteria of results precision and repeatability (random and systematic errors values). These variants include the simplest version of the external standard method (I); its modified version (II) that implies the application of an additional standard and averaging not the absolute, but relative peak areas; the commonly used version of the internal standard method (III); and its version modified in a similar manner (IV). Besides, two variants of using a homologue of the target analyte as the internal standard without determining the calibration coefficients are considered (V) and (VI). This topic is of interest for optimization of practical works on chromatography and teaching the subject in general. The requirements to the additional and internal standards are not identical. Any compound (both present in the samples or added to them) can be selected as the additional standards, and precise setting of the