Gas-Liquid Chromatography of Flavone Ethers.

Separation and identification of flavone, flavonol, isoflavone and flavanone aglycones by capillary column gas chromatography

“…Also a comparison of the differences between the t R values of chrysin (2), 18.74min, and galangin (14), 19.17 min, with those of apigenin (5), 37.06 min, and kaempferol (15), 33.82 min, respectively, suggests that very much longer retention times result with the addition of an ether group to the 4'-position, whereas smaller differences are observed for the t R when an ether group is added to positions 3 (chrysin to galangin) or 5 (daidzein to genistein, 25.92 to 27.59 min). These results are in agreement with those of Nordstrom and Kroneld (1972) obtained using packed column G C (OV-1 and OV-17 stationary phases). The ether groups in positions 5 and 5' appear to have a slightly different effect on the retention times of flavonoids as the flavonols, robinetin (17) and quercetin (18) have retention times of 39.36 and 40.07 min, respectively.…”

“…These techniques are, however, time consuming, limited in separation power or require purified compounds. Adoption of packed column gas chromatography (GC) (Vanhaelen and Vanhaelen-Fastre, 1980;Katagi et al, 1973;Nordstrom and Kroneld, 1972;Hemingway and Hillis, 1969;Furuya, 1965) and, recently, high performance liquid chromatography (HPLC) (Sendra et al, 1988;Heimhuber et af., 1988;Tomas-Barberan et af., 1990;Van De Casteele et af., 1982) for the analysis of flavonoid aglycones greatly improves the speed of their identification; however, complex mixtures of these compounds are still poorly resolved. Therefore, in m a n v natural product analyses a method with greater resolution and better sensitivity is required.…”