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The chemical compatibility of preservatives
Jun 11, 2018

In the use of preservatives, great attention should be paid to the compatibility of various raw materials. Compatibility is the process of reducing the effect of preservatives with the components, packing materials and specific substances of the contents, causing the effect to decrease, even to the contrary, and to increase the efficiency. If it is the compatibility of the failure, it should be paid more attention. The following aspects are for reference only. It is necessary to accumulate, sum up and supplement in the development and production process of the actual formula, so as to be able to master the chemical compatibility of preservative as comprehensive as possible.

1) some of the ingredients in cosmetics such as carbohydrates, talcum powder, metal oxides, cellulose and so on will absorb preservatives and reduce their potency.

2) the products contain starch substances, which can affect the bacteriostatic effect of the sodium paraben ester.

3) high concentration of protein (amino acid), on the one hand, may form protective layer by microorganism to reduce the bacteriostasis activity of preservative, on the other hand, it can promote the growth of microorganism.

4) metal ions, such as Mg2+, Ca2+ and Zn2+, have a great influence on the activity of preservatives. In general, excessive metal ions are easy to form insoluble or catalyzed oxidation in spices, lubricants, natural or sensitive compounds.

5) preservatives can form hydrogen bonds with certain components of cosmetics, such as sorbic acid and some components, or chelates (such as iron ions in thickeners), and reduce the effectiveness of the anticorrosion system by "binding" or "consumption".

6) a small amount of surfactants can increase the permeability of the antiseptic to the cell membrane, and have synergistic effect, but when the amount is large, the micelles will form, attract the preservatives in the water phase, reduce the content of the preservatives in the water phase, and affect the bactericidal efficacy of the antiseptic.

7) some preservatives and surfactants, such as sulfate (ester), carbonate (ester), nitrogen containing surfactant, and pigment fluorescent dye, and packaging materials (plastic, metal, rubber), affect the effectiveness of preservatives, but also damage the quality of the products.

8) non-ionic and high ethoxy substances will affect the activity of the lipid compounds.

9) sulfite affects the activity of isothiazolidone and methyl dibromopamyl two nitrile. Some people may say that I do not contain sulfite in my formula, and it should be fine. But don't forget, for example, sodium sulfite is a common raw material decolorant, and may as well confirm with the raw material supplier whether there is sulfite in the raw material.

10) some plastics can adsorb the activity of preservatives (e.g., paraben esters). Therefore, it is very important to test the product in its final package to ensure that it is adequately preservative.

11) the effects of preservatives on the surface tension of deionized water, the foaming property of the product, the solubility of the components, the color color of the pigment, the fragrance of the perfume, the biological activity of the active factors, should be considered.

In terms of compatibility and efficiency, the most typical example is:

If the formula contains more than 15% ethanol, no other preservatives will be needed. Similarly, Zinc Oxide, which contains sunscreen and prescription for urine eruption, has its own antimicrobial properties. If the content of the glycol is high, it can improve the effect of preservative and can even control the environment needed for the survival of microorganism by combining with free water, so as to reduce the effect of adding or not adding other preservatives.

The discussion on the system is mainly focused on the need for Preservatives in products such as oil in water, silicone oil or water. The fact is, even if we know that microbes can't grow without water, even if we know that the external phase of these systems does not contain water, do not ignore the moisture in the air. A small amount of moisture may just stay on the surface of the product, but this is enough to cause microbial contamination of the product. Therefore, phenoxy alcohol and other preservatives with certain volatile vapor pressure can play a preventive role in this kind of microbiological pollution.