Citric acid trisodium salt dihydrate
INCI Name SODIUM CITRATE
CAS # 68-04-2 / 6132-04-3
EC # 200-675-3
Sodium citrate is the sodium salt of citric acid and is an edible, natural, chelating and buffering agent. Buffers are ingredients that maintain the pH stable and relatively constant. The pH would not change by addition of small acids or bases.
Buffers are specially needed when working with a certain group of natural emulsifiers, the citrates such as Glyceryl Stearate citrate, polyglyceyl-x citrate, polyglyceryl-x stearate citrate and co.. With these emulsifiers, the pH of the lotions drops over time and it might lead to overall instability of the lotion. By buffering the lotion, the pH would remain constant. The most common buffers for cosmetics are sodium lactate/lactic acid (pH around 4.2), or sodium citrate (pH around 5).
Sodium cirtate is a water soluble white powder.
0.1-0.5% in the water phase. You can add it from the very beginning to the water phase or dissolve it in a small portion of water and add it during the cool down phase.