Efficiency of gas chromatographic analysis of terpens and terpenoids of sources of aromatic substances, taking into account the polarity of the stationary phase

摘要

Introduction. The aim of the study is to increase the efficiency of gas chromatographic analysis of terpenes and terpenoids based on the polarity of the stationary phase. Materials and methods. It is used a model matrix №1 from a mixture of terpenes and a model matrix №2 from a mixture of terpenoids, obtained by preparative isolation in individual composition with confirmation of purity of isolation by Kovach index (IK). The analysis was performed on a chromatograph GC 8000 series, carrier gas – helium, detector – flame ionization (FID). The criteria for selecting SP GC analysis according to the Rorschneider polarity system were used. Results and discussion. The separation of terpenoids (polar AS) into non-polar SP, the bonds inherent in polar molecules (dipole or hydrogen bonds) do not occur, so terpenoids are kept on non-polar SP SE-30 much weaker than on polar SP Carbowax 20M. The higher the values of Rs, the more efficient the gas chromatographic system of separation of terpenoids. For the column with SP Carbowax 20M Rs = 1.67, for the column with SP SE-30 Rs = 1.16. The quantitative characterization of the universality of the studied SP with respect to the separation of terpenoids by polarity is the difference of the Kovach GIC indices. So for linalool on SP SE-30 – IR=1093, for Carbowax20M – IR = 1582. This means that less polar terpenoids will leave the gas chromatographic column earlier for more polar AS while ensuring complete separation of the complex mixture and the possibility of reliable and reproducible installation component composition of the prototype. The retention time of terpenes increases with decreasing polarity of SP. Of the two experimental SP, the nonpolar SP SE-30 has a greater affinity for terpenes of the model matrix №1, which precludes obtaining on chromatograms of unresolved peaks for a critical pair of components with close Tboil. The calculated values according to the Rorschneider polarity system indicate the different polarity of the studied SP and the manifestation of characteristic intermolecular forces. When separating critical pairs of terpene hydrocarbons with close Tboil (α-terpinene 172.5 oC, d-limonene 173 oC, α-phellandrene 172 oC) on a non-polar stationary phase (SE-30=4.40) the yield of components from the column is separated. peak. The use of a low-polar stationary phase (HP5ms, Rp 15) provides a consistent output of critical pairs of terpene hydrocarbons by individual peaks in Tboil. Conclusion. The results of the research allow us to increase the reproducibility of gas chromatographic analysis of sources of aromatic substances, as well as to choose SP, which can be interchangeable and provide a similar separation.