Ethylhexylglycerin is a frequently used multifunctional additive. Besides its deodorant efficacy, it is an excellent booster of many traditional preservatives and other antimicrobial substances. It was introduced into the personal care market by schülke as sensiva® SC 50; a product with outstanding quality and comprehensive safety data.
The stabilization of ethylhexylglycerin in sensiva® SC 50 guarantees that the high purity is maintained for the entire shelf–life of the material. This stabilization system has been patented by schülke. Unstabilized ethylhexylglycerin can form unidentified impurities with unknown toxicological profiles during storage.
The safety of sensiva® SC 50 is ensured by this high purity grade of ethylhexylglycerin having an extremely low impurity profile. Due to its patented stabilization, this purity is ensured for the entire shelf-life of the material. Beyond that, sensiva® SC 50 has been used in toxicological studies showing that no side effects coming from its few impurities are to be expected.
sensiva® SC 50-grade ethylhexylglycerin does not pose an increased risk for acquiring a contact allergy after exposure. This was proven in sensitization assays to determine the allergic potential according to Magnusson-Kligman and a local lymph node assay (LLNA).
Other qualities of ethylhexylglycerin without stabilization are now available to the personal care market. Depending on the origin, a significant portion of unknown impurities can be present in the fresh material. Additionally, these variants may not guarantee a constant quality. Due to the ether-function, decomposition can occur in unstabilized ethylhexylglycerin. Thus, more impurities with unknown toxicological profiles can develop during storage. Against this background, it should be considered that the use of impure material could provoke an increased risk of allergies not originally triggered by the main substance, thereby potentially discrediting a valuable molecule.
The Issue of Aging
Many organic substances undergo oxidative degradation (reactions). Specifically, ethers have the potential of forming peroxides if exposed to air. This is also a concern for polyethers, like ethoxylated surfactants, as has been reported in the past. Several different breakdown products can be expected from primary oxidation reactions, like alcohols, ketones, aldehydes and carboxylic acids. All of these categories of substances are reactive enough to undergo secondary reactions which each other.
Additionally, 1,2-diols undergo oxidative cleavage reactions, known as glycol cleavage. This reaction is often used for structure determination of sugars. Ethylhexylglycerin is a glycerol ether which bears both functional groups, ether and diol, in the same molecule. This makes it sensitive to ageing reactions under the influence of air.
Fresh sensiva® SC 50 shows a purity of more than 99%, which is exceptionally high for cosmetic raw materials. To keep this purity for the entire shelf-life, schülke has developed a protection technology utilizing stabilizers, like antioxidants.
As incompatibilities with the skin, such as irritations and sensitization, are the most threatening side effects of the use of cosmetic products, stability of the raw materials, as well as finished products, is of essential importance. Figure 1 shows a gas chromatogram of freshly distilled ethylhexylglycerin. Aside from the main peak, there are just a few very small signals that represent by-products and impurities in an amount of less than 200 ppm each. Due to the stabilization technology, sensiva® SC 50 retains this low impurity profile for its entire shelf-life of three years.
Figure 2 shows the chromatogram of aged, unstabilized ethylhexylglycerin. Many additional peaks can be seen, representing unknown degradation products with an amount of up to 2.5 %. The well-defined material has changed to a complex mixture of potentially critical substances.
Ethylhexylglycerin becomes a very stable molecule when it is stabilized with tocopherol. The safety of sensiva® SC 50, the stabilized quality of ethylhexylglycerin, has been tested and proven in comprehensive toxicity studies by schülke. The constant purity guarantees that no degradation products develop during storage for a minimum of three years.
Unstabilized, aged ethylhexylglycerin shows many breakdown products that can develop during storage. Unidentified impurities with unknown toxicological profile can negatively influence the safety of the product.
The use of ethylhexylglycerin in cosmetic products is increasing steadily, resulting in a higher exposure to consumers. To insure the safety of the consumer, it is of prime importance to verify the quality of ethylhexylglycerin and to ensure the stability over the entire shelf-life of the finished product. This is guaranteed by the use of sensiva® SC 50 with schülke’s patented stabilization system.