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Li Q.,Chongqing Medical and Health School Fuling | Zhang Z.,Chongqing Medical and Health School Fuling | Yao W.,Chongqing Medical and Health School Fuling | Li J.,Chongqing Medical and Health School Fuling | And 2 more authors.
Analytical Methods | Year: 2015

The dienol of ascorbic acid was observed to have a strong reducing power in a 1.44 M HCl buffer solution, and could reduce Fe3+ to Fe2+. The resulting Fe2+ was allowed to react with K3Fe(CN)6 to form the ion-association complex Turnbull's blue, which resulted in the enhancement of resonance Rayleigh scattering (RRS), second order scattering (SOS) and frequency doubling scattering (FDS). The maximum scattering intensities occurred at wavelengths of 374 nm, 540 nm and 395 nm, respectively. The scattering intensities of the three methods were proportional to the concentration of ascorbic acid in a certain range. RRS was found to be the most sensitive method here, and its detection limit for ascorbic acid was 5.0 ng mL-1. The experimental conditions were optimized and the effects of coexisting substances were evaluated. The method showed excellent selectivity, because relatively high amounts of common ions, acid groups, urea, amino acid, saccharides and protein were found not to influence the measurement. Accordingly, a novel, rapid, convenient, sensitive and selective RRS method for determination of ascorbic acid concentration has been proposed, and applied to detect ascorbic acid in tablets and human serum samples with satisfactory results. The reaction mechanism and causes of the resonance light scattering intensity enhancement are also discussed. © 2015 The Royal Society of Chemistry.

Li Q.,Chongqing Medical and Health School Fuling | Yang J.,Chongqing Three Gorges University | Tan X.,Southwest University | Zhang Z.,Chongqing Medical and Health School Fuling | And 2 more authors.
Luminescence | Year: 2016

A novel method that uses acridine orange (AO) to detect indigo carmine (IC) in soft drinks was developed. The method is highly sensitive and is based on a resonance Rayleigh scattering (RRS) technique. In Britton-Robinson (BR) buffer solution, pH 4.3, the weak RRS intensity of AO was greatly enhanced by the addition of IC, with the maximum peak located at 332 nm. Under optimum conditions, it was found that the enhanced RRS intensity was proportional to the concentration of IC over a range of 2-32 × 10-6 mol/L. A low detection limit of 2.4 × 10-8 mol/L was achieved. The sensitivity and selectivity of the method are high enough to permit the determination of trace amounts of IC without any significant interference from high levels of other components such as common anions and other amino acids. Finally, the concentration of IC in three different soft drinks was determined with satisfactory results. © 2016 John Wiley & Sons, Ltd.

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