Oxybenzone Oxidation

The oxidation of oxybenzone was attempted with a reaction of oxybenzone, hydrogen peroxide, and horseradish peroxidase.

Making the Samples For Enzymatic Oxidation

Our actual samples to be tested required the making of a 2 mM oxybenzone pH 5 buffer stock solution, a hydrogen peroxide stock solution, and a horseradish peroxidase solution.

2 mM Oxybenzone Buffer Stock Solution

Combined 50 mL of dioxane, 50 mL of pH 5 buffer solution, and 45.7 mg of oxybenzone in a bottle. Added the oxybenzone to the dioxane, and then added the buffer solution.

Hydrogen Peroxide Stock Solution

Measured 5 mL of water into a scintillation vial. Added 283 microliters of 30% hydrogen peroxide to the water. This provided a hydrogen peroxide solution of about 0.413 M.

Horseradish Peroxidase Stock Solution

Preparing the Final Samples

Measured out 5 mL of the 2 mM oxybenzone buffer stock solution into 4 different scintillation vials. Added hydrogen peroxide solution in different amounts to each vial (6 microliters, 12 microliters, 18 microliters, and 24 microliters). Add 10 microliters of horseradish peroxidase solution to each vial.

Unfortunately, our enzymatic oxidation was unsuccessful, so our focus turned to chemical oxidation.

Making the Samples For Chemical Oxidation

2 mM Oxybenzone Buffer Stock Solution

Combined 50 mL of dioxane, 50 mL of pH 7 buffer solution, and 45.7 mg of oxybenzone in a bottle. Added the oxybenzone to the dioxane, and then added the buffer solution.

Potassium Permanganate Stock Solutions

2mM Potassium Permanganate Stock Solution

• Dissolved 0.0316 g of potassium permanganate in 100 mL of RO water.

4mM Potassium Permanganate Stock Solution

• Dissolved 0.0632 g of potassium permanganate in 100 mL of RO water.

10mM Potassium Permanganate Stock Solution

• Dissolved 0.158 g of potassium permanganate in 100 mL of RO water.

20mM Potassium Permanganate Stock Solution

• Dissolved 0.316 g of potassium permanganate in 100 mL of RO water.

Preparing the final samples

Added 5 mL of the oxybenzone buffer stock solution to a scintillation vial. Then added 5 mL of the 1 mM Potassium Permanganate Stock Solution to the same vial that contained the oxybenzone buffer solution. Mixed solution thoroughly. This vial now contained 1 mM oxybenzone solution and 1 mM potassium permanganate solution once dilution was accounted for. This process was repeated with the rest of the potassium permanganate solutions.

g KMnO4	Concentration of Stock Solution KMnO4 (mM)	Concentration of KMnO4 After Dilution (mM)	Concentration of Oxybenzone After Dilution (mM)
0.0316	2	1	1
0.0632	4	2	1
0.158	10	5	1
0.316	20	10	1

Data

Figure 1. Graph of oxybenzone dissolved in methanol.

Figure 3. Representation of the Oxidation of Oxybenzone and Oxidation Products.