Comparative characterization of different variants of quantitative chromatographic analysis using external and internal standards
Authors:   St. Petersburg State University, Institute of Chemistry, Zenkevich Igor G. , Agafonov Oleg V. ,   St. Petersburg State University, Institute of Chemistry, Aleksandrov Timofei S. ,   St. Petersburg State University, Institute of Chemistry, Barbayanov Kirill A. ,   St. Petersburg State University, Institute of Chemistry, Valov Nikita R. ,   St. Petersburg State University, Institute of Chemistry, Vlassova Vassilissa ,   St. Petersburg State University, Institute of Chemistry, Znamenskaya Ekaterina A. ,   St. Petersburg State University, Institute of Chemistry, Kim Mia D. ,   St. Petersburg State University, Institute of Chemistry, Markova Ulyana O. ,   St. Petersburg State University, Institute of Chemistry, Morgacheva Violetta P. ,   St. Petersburg State University, Institute of Chemistry, Nizov Egor R. ,   St. Petersburg State University, Institute of Chemistry, Ogurtsova nna D. ,   St. Petersburg State University, Institute of Chemistry, Pavlova Ksenija V. ,   St. Petersburg State University, Institute of Chemistry, Pantin Andrew V. ,   St. Petersburg State University, Institute of Chemistry, Simdianov Ivan V. ,   St. Petersburg State University, Institute of Chemistry, Taishev Arthur E. ,   St. Petersburg State University, Institute of Chemistry, Chechueva Daria E. ,   St. Petersburg State University, Institute of Chemistry, Shatkovskii Denis P. ,   St. Petersburg State University, Institute of Chemistry, Shilov Roman A. ,   St. Petersburg State University, Institute of Chemistry
Published: February 2024

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 their concentrations is not required. It is only necessary to ensure their equal concentrations in the analyzed and reference solutions. It is shown that the modified versions of the external and internal standard methods are characterized by the equal relative standard deviations of the results. The minimal relative standard deviations of the results are typical for the variants implying the use of an additional (II) or an internal (IV) standard and the averaging the ratio of peak areas of target analytes and such standards. The systematic errors of determinations appeared to be minimal for the same variants. Controlling the values of the calibration coefficients is informative for revealing the possible distortions of the composition of samples due to the partial evaporation of volatile constituents in the course of handling such samples.