IADR Abstract Archives
Oxidation of Blue Dye With Hydrogen Peroxide as a Function of pH
Objectives: To evaluate the effects of pH on oxidation rate of blue food dye (BD) on exposure to hydrogen peroxide at various pHs by measuring absorbance over time.
Methods: Time course reaction of 0.01 ml of dye (Brilliant Blue FCF, 0.01 M) and hydrogen peroxide (HP, 0.01 M) with 0.05 ml of various pHs (4, 5, 6, 7, 8, 9, 10, 1M) buffers were evaluated. The absorbance of seven different mixture aliquots at time intervals of 0-, 10-, 20-, 30-, 45- and 60-minute from the beginning of the reaction were analyzed using a spectrophotometer (Power Wave X-1) on six samples of each reaction at peak wavelength of 630 nm. Possible end products were observed from the evaporated reaction mixture in the pH 8 buffer solution after 24-hour reaction. One-way ANOVA, followed by the post-hoc Tukey’s HSD test, was conducted to detect the difference in absorbance values among seven pH levels at each time point. Correlation between pH and absorbance values under different conditions were also evaluated using Pearson correlation test or Spearman rank correlation test.
Results: The effect of pH on absorbance (result of reaction progress) was significant at all time points over a one-hour reaction among the seven pH values (p<0.0001 in each instant). The greatest significant decrease in absorbance was observed at pH 8 for every respective time point. Significant correlation between pH and absorbance values at 20 minutes was noted (r=-0.79, p=0.0362). This suggests that the greatest rate of oxidation occurs at 20 minutes after beginning of the reaction which implies the highest amount of breakdown products formed. When BD and HP are reacted at pH, the end byproducts formed were volatile.
Conclusions: BD on exposure to HP is pH-dependent, with pH 8 showing the greatest significant change.
Methods: Time course reaction of 0.01 ml of dye (Brilliant Blue FCF, 0.01 M) and hydrogen peroxide (HP, 0.01 M) with 0.05 ml of various pHs (4, 5, 6, 7, 8, 9, 10, 1M) buffers were evaluated. The absorbance of seven different mixture aliquots at time intervals of 0-, 10-, 20-, 30-, 45- and 60-minute from the beginning of the reaction were analyzed using a spectrophotometer (Power Wave X-1) on six samples of each reaction at peak wavelength of 630 nm. Possible end products were observed from the evaporated reaction mixture in the pH 8 buffer solution after 24-hour reaction. One-way ANOVA, followed by the post-hoc Tukey’s HSD test, was conducted to detect the difference in absorbance values among seven pH levels at each time point. Correlation between pH and absorbance values under different conditions were also evaluated using Pearson correlation test or Spearman rank correlation test.
Results: The effect of pH on absorbance (result of reaction progress) was significant at all time points over a one-hour reaction among the seven pH values (p<0.0001 in each instant). The greatest significant decrease in absorbance was observed at pH 8 for every respective time point. Significant correlation between pH and absorbance values at 20 minutes was noted (r=-0.79, p=0.0362). This suggests that the greatest rate of oxidation occurs at 20 minutes after beginning of the reaction which implies the highest amount of breakdown products formed. When BD and HP are reacted at pH, the end byproducts formed were volatile.
Conclusions: BD on exposure to HP is pH-dependent, with pH 8 showing the greatest significant change.