Acid-Stable Food Dyes

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Justin Hopkins CHM 244B Investigating the Components & Properties of Acid-Stable Food Dyes: Abstract The purpose of this experiment is to examine, ascertain, and characterize the antioxidant properties of acid stable food dyes. Specifically examining the family of food dyes known as anthocyanins, by subsequently converting them to anthocyanidins in order to characterize the compounds by UV-Vis spectroscopy and chromatography. The relative concentrations of anthocyadins in each sample in order of blueberry, raspberry, and blackberry: 3.6 x 10^-5 mol/g, 1.0135 x 10^ -5 mol/g, and 5.8 x 10^ -6 mol/g. The blueberry was found to have the highest concentration and quantity of anthocyanins, followed by the raspberry, and lastly the blackberry…show more content…
This is done to ensure the atmosphere within the chamber is saturated with the solvent as well. Using one piece of chromatography paper 3 spots were made, one for blueberry, raspberry, and blackberry. Each went through the same aforementioned isolation process from a powdered form. The spots were placed on a line drawn horizontally across the paper with a pencil. The chromatography paper was then wrapped around a thin copper wire just enough to suspend it, and placed into the chamber with the other end of the paper in the mobile phase and the chamber was covered again. When the mobile phase was near the top of the paper, it was removed from the chamber and the solvent line was marked with a pencil. The paper was allowed to dry in the hood then each spot was marked and measured. The Rf values were calculated for the mobile phase, and compared with the results of the mobile phase of formic acid. The same process is done again using the hydrolyzed (anthocyadin) sample, and the results were again compared across all berries, and mobile phases before and after…show more content…
Two solvents were used as the mobile phase before hydrolysis and in turn came up with differing results. The butanol solvent is a highly polar solvent as is the stationary phase of the chromatography system. Table 1 shows the results of putting the more polar anthocyandins in a highly polar mobile phase, and stationary phase. The resulting Rf values were very similar as the berry analytes were held in place by the stationary phase as expected of a polar analyte. However, the highly polar mobile phase interfered with this process by binding just as strongly to the analyte and subsequently dragging the binding anthocyanin up the strip. This process is quite slow due to the analytes binding back forth to each phase in the strip. The Rf differentiation being so little is also due to this binding of phases, the polarities of the phases are so high that the difference in polarity of the analytes is negligible. The formic acid mobile phase produced much higher Rf values for each berry, and also showed greater differentiation between each berry’s Rf value. Hydrolysis of the anthocyanins in the butanol mobile phase produced a pronounced difference in Rf values. The Rf values in butanol elevated much closer to the formic acid Rf values originally. Suggesting that the polarities of the hydrolyzed anthocyanins had a pronounced change- becoming far more non-polar. This change would enable the

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