کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1234543 | 968829 | 2009 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Kinetic model for astaxanthin aggregation in water–methanol mixtures Kinetic model for astaxanthin aggregation in water–methanol mixtures](/preview/png/1234543.png)
The aggregation of astaxanthin in hydrated methanol was kinetically studied in the temperature range from 10 °C to 50 °C, at different astaxanthin concentrations and solvent composition. A kinetic model for the formation and transformation of astaxanthin aggregated has been proposed. Spectrophotometric studies showed that monomeric astaxanthin decayed to H-aggregates that after-wards formed J-aggregates when water content was 50% and the temperature lower than 20 °C; at higher temperatures, very stable J-aggregates were formed directly. Monomer formed very stable H-aggregates when the water content was greater than 60%; in these conditions H-aggregates decayed into J-aggregates only when the temperature was at least 50 °C. Through these findings it was possible to establish that the aggregation reactions took place through a two steps consecutive reaction with first order kinetic constants and that the values of these depended on the solvent composition and temperature.
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 73, Issue 1, July 2009, Pages 157–162