Gas–liquid Chromatography of Some Flavonoid Compounds and Hydroxy Diphenyls

Gas–liquid chromatography of the methyl ethers of 36 flavones, flavanones, isoflavones, and chalkones, 2 chromones, and 9 hydroxy diphenyls was carried out, using SE-30 silicone polymer as liquid phase. The results obtained show that this technique can be used for the separation, isolation, and identification of milligram amounts of these compounds. The influence of methylation, acetylation, and hydrogen bonding was demonstrated and is discussed. Dehydration of a 2-hydroxyisoflavanone to the corresponding isoflavone and isomerization between some flavanones and chalkones were encountered. No linear relationship between the number of substituents and retention time was obtained, indicating that substituents at different positions of a flavonoid nucleus influence the retention characteristics in a different manner. This was especially noticeable with some 3- and 5-substituted flavones, but in other instances the difference in retention times was also sufficient to differentiate between position isomers.