Green extraction of prostaglandin analogs in cosmetics using deep eutectic solvents and detection via LC-MS/MS

Prostaglandin analogs (bimatoprost, travoprost, tafluprost, etc.) have similar effects to prostaglandins and are effective drugs for treating glaucoma. These compounds exhibit abnormal reactions such as causing eyelash growth, with several cases being reported of people purchasing them to increase eyelash growth; however, some cases have reported side effects such as pigmentation and dry eyes. In the Republic of Korea, cosmetics are not medicines for treating diseases; therefore, cosmetics cannot contain drugs or have labels that could mislead people. However, there are cases in which products claim to elongate and enrich eyelashes. Concerns about the abnormal reactions of these products are constantly growing, and the absence of analytical methods for illicit compounds (prostaglandins and their analogs) in cosmetics (eyelash growth serums) renders monitoring challenging. Accordingly, in this study, we sought to develop an LC-MS/MS method for facile and fast analysis of compounds illegally mixed into eyelash growth serums. Green analytical chemistry has recently emerged because of environmental concerns. In line with this trend, we developed an optimal method by comparing the methods mainly used in cosmetic pretreatment (solvent extraction, QuEChERS, and solid phase extraction) with a method using deep eutectic solvents (DESs), which is an eco-friendly solvent. As a result of validation according to the International Conference on Harmonization guidelines, the limit of detection was 0.20-9.34 ng/mL, and the limit of quantification was 0.60-28.31 ng/mL. Recovery, linearity, precision, and accuracy were within acceptable ranges. Additionally, using the Analytical GREEnness calculator and complex green analytical procedure index tools, we confirmed that the method using the DES was greener than the other methods. In this study, we developed an analytical method for illicit compounds contained in eyelash growth serums, offering an eco-friendly approach for the prevention of the distribution of illegal cosmetics.