Zinc Citrate Solubility and Use in Toothpaste
Question
When dissolving Zinc Citrate ([url=https://www.myskinrecipes.com/shop/oral-care-%E0%B8%94%E0%B8%B9%E0%B9%81%E0%B8%A5%E0%B8%8A%E0%B9%88%E0%B8%AD%E0%B8%87%E0%B8%9B%E0%B8%B2%E0%B8%81/1232-zinc-citrate.html:2fez46cb]Zinc Citrate[/url:2fez46cb]) in water at 70-80°C, the water becomes cloudy white. If left standing, the water and powder separate. Can this cloudy solution be used directly in toothpaste?
Answer
Understanding Zinc Citrate Solubility in Toothpaste
It's normal for Zinc Citrate dissolved in water at 70-80°C to appear cloudy and separate upon standing if the concentration exceeds its solubility limit. While using warm water helps accelerate the dissolution process, the maximum amount of Zinc Citrate that can dissolve in water is limited to about 0.6% (6mg/ml).
If you are using a concentration higher than this, the excess will not fully dissolve, resulting in the cloudy appearance and separation of undissolved particles from the water.
Zinc Citrate is indeed suitable for use in toothpaste formulations. However, using a solution where the active ingredient is not fully dissolved and is separating is generally not recommended for toothpaste. This can lead to uneven distribution of the Zinc Citrate throughout the product, affecting its efficacy and potentially the texture.
To ensure proper incorporation into your toothpaste, it's best to use Zinc Citrate at a concentration that can remain dissolved or ensure it is evenly dispersed within the toothpaste base to maintain homogeneity.
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