Adding Alpha Arbutin to Vitamin C E Ferulic Kit

Based on the information, you can add 1g of Alpha Arbutin to the Vitamin C E Ferulic kit before adding the Vitamin C.

Here's why:

• The final pH of the Vitamin C E Ferulic kit after mixing with Vitamin C is approximately 3.5.
• Alpha Arbutin is effective within a pH range of 3.5 to 6.5.

Therefore, the pH of the mixed kit is suitable for Alpha Arbutin to work effectively.

However, it is recommended to first try the Vitamin C E Ferulic kit on its own. The kit is already effective for skin brightening, and it might meet your needs without the additional cost of Alpha Arbutin.