Novel and sensitive methods for the determination of dopamine based on the resonance Rayleigh scattering, second-order scattering and frequency doubling scattering quenching effects.

Yan Ma, Nian Bing Li, Hong Qun Luo

Index: Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 73(4) , 747-51, (2009)

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Abstract

Three novel methods were designed for the determination of dopamine (DA) by means of the quenching effects on resonance Rayleigh scattering (RRS) and non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities. In Britton-Robinson buffer medium (pH 6.02), I(3)(-) could react with DA to produce I(-), which resulted in the decreases of the RRS, SOS and FDS intensities of the ethyl violet (EV)-I(3)(-) system, and the decreases of scattering intensity (DeltaI) were directly proportional to the concentrations of DA in a certain range. The detection limit (3sigma) for DA was 0.0195 micromol/L for the RRS method, 0.286 micromol/L for the SOS method and 0.0985 micromol/L for the FDS method, respectively. In this work, the characteristics of absorption, RRS, SOS and FDS spectra of this reaction have been studied; the optimum reaction condition and influencing factors have been investigated. The methods were applied to the determination of DA in pharmaceutical samples with satisfactory results.