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Separation and purification of rebaudioside A from extract of Stevia Rebaudiana leaves by macroporous adsorption resins

Anvari M., Khayatian G.

Polish Journal of Chemical Technology

2016

Vol. 18, nr 1

127--132

The separation and purification of rebaudioside A from Stevia rebaudiana crude extracts (Steviosides) by macroporous resin were optimized by Taguchi orthogonal array (OA) experimental design methodology. This approach was applied to evaluate the influence of five factors (adsorption temperature, desorption time, elution solution ratio, adsorption volume and type of resin) on the rebaudioside A yield. The percentage contribution of each factor was also determined. The results showed that elution solution ratio and adsorption volume made the greatest (59.6%) and the lowest (1.3%) contribution, respectively. The results showed that the Taguchi method is able to model the purification of rebaudioside A process well (R2 > 0.998) and can therefore be applied in future studies conducted in various fields. Adsorption temperature 35°C, desorption time 60min, elution solution ratio 3, adsorption volume 200ml and HPD-400 as resin were the best conditions determined by the Taguchi method.

Conductance Study of the Complexation of NH4+ and Tl+ Ion with Different Crown Ethers in Binary Acetonitrile-Methanol Mixtures

Khayatian G., Karoonian F. S., Vaziri S.

Polish Journal of Chemistry

2008

Vol. 82, nr 3

537-545

A conductance study of the interaction of NH4 + and Tl+ ion with 18-crown-6 (18C6), ditertbutyl-dicyclohexyl-18-crown-6 ((t-but)2DC18C6), diaza-15-crown-5 (DA15C5), dibenzo-21-crown-7 (DB21C7) and dibenzo-24-crown-8 (DB24C8) in acetonitrilemethanol mixture was carried out at 25.0š0.1°C. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the order of DA15C5 > 18C6 > DB21C7 > (t-but)2DC18C6 > DB24C8, in the case of Tl+ ion in 100% MeOH, and in the order of: DA15C5 > 18C6 > (t-but)2DC18C6 > DB21C7 > DB24C8 for the NH4 + ion in 100% AN and AN-MeOH mix tures. The sta bil i - ties of the complexes for NH4 + and Tl+ ions varied in versely with the Gutmann donicity of the solvent with the ex cep tion of DA15C5-Tl+ complexes. The in fluence of substituents on the polyether ring and cavity size is discussed.