Pch. Hollman et al., FLUORESCENCE DETECTION OF FLAVONOLS IN HPLC BY POSTCOLUMN CHELATION WITH ALUMINUM, Analytical chemistry, 68(19), 1996, pp. 3511-3515
Flavonols are dietary antioxidants which may prevent coronary heart di
sease, To be able to study absorption of flavonols in humans, we devel
oped a postcolumn derivatization with aluminum for HPLC with fluoresce
nce detection, Variables governing postcolumn chelation, such as water
content, buffer, organic modifier of the eluent, concentration of Al3
+, presence of acetic acid in the postcolumn reagent, and temperature,
were studied and optimized. Of the flavonoids, only flavonols that co
ntain a free 3-hydroxyl and 4-keto oxygen binding site form fluorescen
t complexes with Al3+, The method has a detection limit of 0.15 ng/mL
for quercetin, 0.05 ng/mL for kaempferol, 0.45 ng/mL for myricetin, an
d 0.05 mg/mL for isorhamnetin, thus improving detectability of quercet
in 300-fold as compared to that possible with UV detection, The reprod
ucibility relative standard deviation of the method is 1.4%. This extr
emely sensitive method enables, for the first time, determination of f
lavonols in body fluids after consumption of a normal diet.