Vitamin C Dissolution Problem in Skinceuticals-like Formula
Question
I am experiencing a dissolution problem with L-Ascorbic Acid in a formula similar to Skinceuticals. I mixed Part A and Part B at 45°C for 1 minute, then added standard grade L-Ascorbic Acid. It did not dissolve even after stirring for a long time (3 days now). I plan to discard this batch and make a new one using L-Ascorbic Acid Ultra Fine. How can I resolve this issue? The formula used was: Part A: DI Water 43.7g, Triethanolamine (TEA) 2.5g (omitted), Ferulic Acid 0.5g, Panthenol 0.5g. Part B: Ethoxydiglycol 20g, Propylene Glycol 10g, Glycerin 3g, Laureth-23 3g, d-Alpha Tocopherol 1g.
Answer
Subject: Re: Problem mixing Vitamin C Skinceuticals formula - Did not dissolve
Hello,
Regarding the issue with your Vitamin C (L-Ascorbic Acid) not dissolving in your Skinceuticals-like formula, there are a few potential reasons:
- Missing Triethanolamine (TEA): You mentioned you did not include Triethanolamine (TEA) in Part A. TEA is listed in the formula to adjust the pH to around 3.7. L-Ascorbic Acid is an acid, and its solubility in water is highly dependent on pH. Without TEA, the pH of your solution is likely too low, significantly reducing the solubility of L-Ascorbic Acid. This is the most probable cause of the dissolution problem.
- Particle Size: You used "ascorbic acid standard". The particle size of standard grade L-Ascorbic Acid can be larger than "ultra fine", making it harder to dissolve, especially if other conditions (like pH) are not optimal. Using the "ultra fine" grade, as you are considering, is a good step as it has smaller particles which dissolve more easily.
- Stirring Time: While 1 minute of stirring is a starting point, complete dissolution might require longer or more vigorous stirring, especially with standard grade L-AA or if the pH is not ideal.
How to fix it:
Unfortunately, it is unlikely that the L-Ascorbic Acid in your current batch will fully dissolve now, and its stability may be compromised after 3 days undissolved. It is best to discard this batch.
For your new batch using L-Ascorbic Acid Ultra Fine:
- Crucially, include ALL ingredients as listed in the formula, including the Triethanolamine (TEA) in Part A.
- Mix Part A and Part B separately as instructed.
- Combine Part A and Part B and heat gently to 45°C.
- Add the L-Ascorbic Acid Ultra Fine.
- Stir thoroughly and patiently. While ultra fine dissolves more easily, ensure you stir until all particles are completely dissolved. This might take longer than 1 minute. Gentle heating at 45°C while stirring will help.
- Once fully dissolved, continue with the rest of the instructions (cooling, adding other ingredients if any, checking pH if possible).
Ensuring the correct pH by including TEA and using the ultra-fine L-Ascorbic Acid with sufficient stirring time should resolve the dissolution issue.
Hope this helps!
Related Products Mentioned
Pure-Ferulic Acid™
Vitamin C (L-ascorbic acid) (Ultra-Fine)
