Hydroxy acids (HAs) are organic acids that contain one or more hydroxyl groups. Alpha-hydroxy acids (AHA), also known as “fruit acids”, are well known for their use in the cosmetics industry, with the concentration normally between four percent and ten percent.
These compounds are included in cosmetic products to improve skin texture and reduce pigmentation and wrinkles.
Due to the rapid development of the cosmetic industry, as people increasingly use cosmetics on a day-to-day basis, the safety of cosmetic products is becoming more important.
Safety necessity
Therefore, the scientists, from Kaohsiung Medical University, Taiwan, deemed it necessary to establish a method to analyze the commercial cosmetic product content of AHAs in cosmetic products.
Capillary electrophoresis (CE), can be used to separate ionic species by their charge and frictional forces and hydrodynamic radius.
Experimental design remains a core area of study in chemometrics and several monographs are specifically devoted to experimental design in chemical applications.
Therefore the scientists used a CD-modified CE method to quantitatively determine seven hydroxy acids used in cosmetic products, for analysis.
Saves time and cost
The developed method involved chemometric experimental design aspects, including fractional factorial design and central composite design. CD was used to enhance the method's separation capability and to explore the interactions between parameters.
Compared to the traditional investigation that uses multiple parameters, the method that used chemometric experimental design was less time-consuming and lower in cost.
In this study, the influences of three experimental variables (phosphate concentration, surfactant concentration, and methanol percentage) on the experimental response were investigated by applying a chromatographic resolution statistic function.
“After optimization and validation, this simple and rapid analysis method was considered to be established and was successfully applied to several commercial cosmetic products,” comments the study author.