Simultaneous Detection of Glabridin, (−)-α-Bisabolol, and Ascorbyl Tetraisopalmitate in Whitening Cosmetic Creams Using HPLC-PAD

A simultaneous analytical method was developed and validated to quantify three lipophilic compounds; namely glabridin (an isoflavonoid isolated from crude licorice), (−)-α-bisabolol (a sesquiterpene alcohol obtained from plant extracts), and ascorbyl tetraisopalmitate (a fat-soluble molecule derived from vitamin C) in functional cosmetic cream using high-performance liquid chromatography (HPLC) coupled with photodiode array detection (PAD). Cosmetic cream samples were extracted with a mixture of acetonitrile and isopropyl alcohol (45:55, v/v) and the target compounds were separated on a C18 column with a gradient mobile phase consisting of deionized water, acetonitrile, and isopropyl alcohol. The detector wavelengths were 228, 202, and 221 nm, for glabridin, (−)-α-bisabolol, and ascorbyl tetraisopalmitate, respectively. The calibration curves showed good linearity with determination coefficients (R 2) ≥ 0.999. The mean recoveries were ranged between 89.8 and 103.9 % with relative standard deviations (RSDs) <5 %. The intra- and inter-day precision was <2 %. The limits of detection (LODs) were 0.03, 0.4, and 4.02 μg mL−1 for glabridin, (−)-α-bisabolol, and ascorbyl tetraisopalmitate, respectively. The method was successfully applied for monitoring 11 market samples, in which glabridin was quantified in the range of 17.5–25 mg 100 g−1, (−)-α-bisabolol in the range of 25.1–677 mg 100 g−1, and 140.6–291.5 mg 100 g−1 for ascorbyl tetraisopalmitate. The proposed analytical method is simple, sensitive, and versatile and can be used for the quantification of lipophilic compounds in cosmetics in a single chromatographic run.