L-Arginine Solubility in Water

Regarding the solubility of L-Arginine in water for cosmetic formulations, based on the product information for L-Arginine (free base), its solubility in water is limited to no more than 1.5%.

This explains why you are encountering issues dissolving 2% in your formula, as this concentration exceeds its maximum solubility in water.

L-Arginine is also known for its high alkalinity (pH 10.5-12.0) and is often used to adjust the pH of formulations upwards. While pH can influence solubility, the general solubility limit provided is 1.5% in water.

To ensure full dissolution, it is recommended to use L-Arginine at a concentration of 1.5% or less in your water phase.