Zulina Abd Maurad

Eye irritation potential: palm-based methyl ester sulphonates

Abstract Aim: To evaluate eye irritation potential of palm-based methyl ester sulphonates (MES) of different chain lengths; C12, C14, C16, C16:18. Methods: The Bovine Corneal Opacity and Permeability test method (BCOP), OECD Test Guideline 437, was used as an initial step to study the inducing effect of palm-based MES on irreversible eye damage. The second assessment involved the use of reconstructed human corneal-like epithelium test method, OECD Test Guideline 492 using SkinEthic™ Human Corneal Epithelium to study the potential effect of palm-based MES on eye irritancy. The palm-based MES were prepared in 10% solution (w/v) in deionized water and tested as a liquid and surfactant test substances whereby both test conducted according to the liquid/surfactant treatment protocol. Results: The preliminary BCOP results showed that palm-based MES; C12, C14, C16, C16:18 were not classified as severe eye irritants test substances with in vitro irritancy score between 3 and the threshold level of 55. The second evaluation using SkinEthic™ HCE model showed that palm-based MES; C12, C14, C16, C16:18 and three commercial samples were potentially irritants to the eyes with mean tissue viability ≤ 60% and classified as Category 2 according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals. However, there are some limitations of the proposed ocular irritation classification of palm-based MES due to insolubility of long chain MES in 10% solution (w/v) in deionized water. Conclusion: Therefore, future studies to clarify the eye irritation potential of the palm-based MES will be needed, and could include; methods to improve the test substance solubility, use of test protocol for solids, and/or inclusion of a benchmark anionic surfactant, such as sodium dodecyl sulphate within the study design.

Performance of Palm-Based C16/18 Methyl Ester Sulphonate (MES) in Liquid Detergent Formulation

Liquid detergents are more convenient than powdered detergents as they dissolve readily in water, generate less dust and dosing is easy. However, the stability of liquid detergents is an issue of concern. Therefore, the objective of this research is to study the formulation requirement to produce heavy-duty liquid detergents based on palm-based methyl esters sulphonate (MES) with desirable properties and performance. MES is produced from renewable and sustainable feedstock suitable to replace the conventional fossil-based surfactant, linear alkyl benzene sulphonates (LAS). Five palm-based liquid detergents (PBLDs) were formulated using C16/18 MES as the primary surfactant. The physical properties, washing performance, stability and biodegradability of PBLDs were evaluated. Performance of the PBLDs was evaluated against two commercial liquid detergents which use LAS and alcohol glucoside as surfactant (benchmark product) and it was found that the PBLDs exhibited excellent performance. PBLDs can be formulated with or without phosphates and still demonstrate good detergency. The stability study of PBLDs indicated that no appreciable hydrolysis occurred. PBLDs exhibited better biodegradability profiles compared to commercial detergent containing LAS. PBLDs passed the 60% biodegradability level within 3 to 8 d, while commercial detergent took 24 d. It was shown that palm-based C16/18 MES could be potentially formulated into liquid detergents and gave better performance than LAS based liquid detergent. Attributes of C16/18 MES should not be overlooked, which include an abundant and naturally derived palm stearin as raw material and environmental safety profiles that are superior to most synthetic surfactants.