The work experimentally shows the possibility of identifying the components of biological systems based on the determination of their retention indices. It has been shown that the retention indices determined by calculation and graphical give identical results.

The paper considers the possibility of determining the content of menthol and its isomers in drugs using gas chromatographic retention indices. The chromatographic parameters of nalkanes (C5–C12, C14) were determined to establish the retention indices by graphic and calculation methods. The retention indices of the components of the studied drugs were determined.