Effect of ph on antioxidant capacity

1. Effect of ph on antioxidant capacity Group Members: Ng Aik Yang (2A1)SiahZhiXuan (2A1) Darryl Hwang (2A2) Timothy Loe (2A3)

2. Hypothesis Hypothesis : The higher the pH, the faster the reaction between antioxidants and free radicals. Null Hypothesis: pH does not affect antioxidant capacity.

3. Rationale To investigate if Alkaline water really helps antioxidants function better to counter the free radicals in our body

4. Methodology Chemicals used: • Different kinds of antioxidants (aqueous). E.g. red tea, ginger tea, vitamin C solution • 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) • Hydrochloric acid (HCl) • Sodium Hydroxide (NaOH) • Salt Solution (NaCl)

5. Methodology Chemicals needed: • ABTS Molecular Formula: C18H18N4O6S4. NH3 • Frequently used by the food industry and agricultural researchers to measure the antioxidant capacities of foods • Blue solution, but converted to a colorless solution after reactions with antioxidants

6. Methodology Test for light absorbance level by putting the cuvette into the UV-Vis Spectrometer, and record the results Put 3ml of ABTS into a cuvette 1 min Record the light absorbance level Add 25µl of antioxidants of varying pH level into the cuvette of ABTS

7. What happens • Antioxidants from the solution will react with the free radicals in the ABTS • The ABTS would turn from blue to colorless gradually as the antioxidants react with the ABTS. • The higher the colour intensity of the solution, the more light will be absorbed. • Thus, by measuring the light absorbance, we can see how much of the ABTS has reacted.

8. variables

9. *Light absorbance = (light absorbance of ABTS with chemicals - original light absorbance of ABTS) divided by original light absorbance of ABTS × 100% Experiment procedures • 4 beakers of the various antioxidants with varying pH values (adjusted with the chemicals, NaOH and HCl) • pH meter used to measure pH • 3 beakers with NaCl solution (control) • One unchanged solution • Add in 3 ml of ABTS into cuvettes and test the absorbance • Put the 25µl of antioxidant in, and start timing • And after shaking, put it in the UV-Vis Spectrometer and wait for 1min • Observe and recorded results obtained

10. Ginger

11. Has a trend that a high pH leads to a higher light absorbance, showing that it has a higher antioxidant capacity • Light absorbance relatively low Ginger

12. Red tea

13. Shows a similar trend with Ginger • Error bars can show that range of results defy trend • Subjective conclusion Red tea

14. Chrysanthemum tea

15. Tie guan Yin

16. Chrysanthemum tea • Both showed two similar dips in terms of graphs. • Error bars show that results between the 5 tests we took were rather consistent • In this case, pH does not affect antioxidant capacity Tie guan Yin

17. GINGER (EXTENDED)

18. General trend shows that antioxidant capacity decrease then increases slowly throughout, with a drastic increase between pH 9.7 – pH 10.5 GINGER (EXTENDED)

19. Conclusion • pH does not affect antioxidant capacity for antioxidant bodies like tea • Different antioxidant bodies might react differently to the ABTS • Alkaline water does not really help antioxidants function better to counter free radicals in our body • Acid-base homeostasis, part of human homeostasis concerning the proper balance of pH, already adjusts the body for anti-oxidant capacity to work at its peak. • Our results fulfill the null hypothesis which would be that pH does not affect antioxidant capacity.

20. challenges we faced • Adjustments of the pH for antioxidant bodies such as fruits • Varying the pH by the number of drops instead

21. General reflections

22. Works Cited • ABTS. In Wikipedia. Retrieved from http://en.wikipedia.org/wiki/ABTS • Wikipedia. [Image ABTS molecule structure]. Retrieved from http://en.wikipedia.org/wiki/File:ABTS.png • Fairy-water watertec Co. Ltd. [Image alkaline water machine]. Retrieved from http://www.ro-filter.com/images/products/ALKALINE_WATER_IONIZER_MANUFACTURER.jpg

23. Thank you for your kind attention!