UV-VIS SPECTROSCOPY TO DETECTION OF QUERCETIN IN PLANTS BY FORMATION OF QUERCETIN-ALUMINUM COMPLEX

Abstract

Nine plant samples were studied from complexation reaction that occurs between aluminum from aluminum chloride (AlCl3) and quercetin. The reaction shows yellow solution, which was spectroscopically evidenced by the bathochromic shift from 360-370 nm to 420-430 nm. Four samples of petals were investigated: white and magenta azalea, burnt yellow lily and dandelion; three leaf samples: aloe, orange and lime; and two peel samples: orange and lime fruits. Among the analyzed samples, only azalea (Rhododendron sp.) white and magenta petals had sufficient quercetin concentration to be detected by UV-Vis spectroscopy and analyzed by quercetin-aluminum complex formation. The interaction between aluminum and quercetin showed a stoichiometry of 2:1, with a binding constant of 3.94 ± 0.34 x 103 mol L-1.