Analytical Sciences

Abstract − Analytical Sciences, 19(7), 1055 (2003).

Interaction between Isopoly-TungsticAcid and Berberine Hydrochloride by Resonance Rayleigh ScatteringSpectrum
Shaopu LIU  and LingKONG
Institute of Environmental Chemistry,Southwest China Normal University, Chongqing, 400715, China
In a weak acid medium, when anisopoly-tungstic acid reacts with berberine to form an ion-associationcomplex, strong resonance Rayleigh scattering (RRS) appears and obviousfrequency-doubling scattering (FDS) as well as second-order scattering(SOS) come into being. The scattering peaks are located at 288 and 369 nmfor RRS, at 290, 370 and 390 nm for FDS, and at 480, 540 and 740 nm forSOS. Under optimum conditions, all three scattering intensities aredirectly proportional to the concentration of berberine and can be appliedto the determination of berberine. The sensitivity of the RRS method isthe highest; the detection limit (3 σ) for berberine hydrochloride is7.6 ng/ml. The method also has good selectivity. It has been applied tothe determination of berberine in pharmaceuticals and goldthread extractswith satisfactory results. In the paper, studies of the existing speciesof isopoly-acid and the component of the ion-association complex arereported and the reasons of enhancement of RRS are discussed.