Hye-Jin Jeong

Simultaneous determination of two Amadori compounds in Korean red ginseng (Panax ginseng) extracts and rat plasma by high-performance anion-exchange chromatography with pulsed amperometric detection.

A new simple, rapid and sensitive high-performance anion-exchange chromatography method with pulsed amperometric detection (HPAEC-PAD) was developed and validated for the simultaneous determination of two Amadori compounds, arginyl-fructose and arginyl-fructosyl-glucose in Korean red ginseng (Panax ginseng) extracts, rat plasma. Separation of the two target analytes was efficiently undertaken on CarboPac PA1 anion-exchange column with isocratic elution (400 mM sodium hydroxide and deionized water (90:10, v/v)) at flow rate 0.7 mL/min within 15 min of single chromatographic run. Under optimized conditions, the detection limits (signal-to-noise ratio equal to 3) were 20 and 25 ng/mL for arginyl-fructose and arginyl-fructosyl-glucose, respectively. Calibration curves of peak area for the two analytes were linear over three orders of magnitude with a correlation coefficients greater than 0.999. The accuracy of the method was tested by recovery measurement of the spiked samples which yielded good results of 94.15-102.62%. This method was successfully applied to the quantification of arginyl-fructose and arginyl-fructosyl-glucose in herbal extracts and in the plasma samples from rat.

Determination of Iron, Copper, Zinc, Lead, Nickel and Cadmium in Cosmetic Matrices by Flame Atomic Absorption Spectroscopy

Metals are commonly used in cosmetic products for blocking ultraviolet light or coloring pigments; however, some metals exceed specific concentrations and can cause serious safety issues such as skin troubles and allergies. It is, therefore, important to measure the exact amount of metal in cosmetic products. However, the exact concentrations of metals in cosmetics that contain many organic and inorganic materials like oils, polymers, waxes, polyols, surfactants, and metallic powders are difficult to analyze due to the matrix effect. In this study, we developed and optimized a method to characterize six different metals (Iron, Copper, Zinc, Lead, Nickel and Cadmium) in cosmetics by using Flame Atomic Absorption Spectroscopy (FAAS). Commercial products in liquid and powder phase were prepared for analysis and spiking solutions were added to the analyte. The method was developed by optimizing acid for decomposition, acid ratio, and sample weight. The recoveries for accuracy test ranged from 92–105% and the linearity correlation coefficients were no less than 0.99. The relative standard deviations (% RSD) for repeatability were between 0.5–2.0%. In addition, robustness and ruggedness test results showed consistent quality of data under different conditions. Consequently, the proposed method is a rapid and simple protocol to determine metals in liquid and powder type of cosmetics with a high confidence level.

Determination of hexavalent chromium in cosmetic products by ion chromatography and postcolumn derivatization.

Chromium hydroxide green [Cr2O(OH)4] and chromium oxide green (Cr2O3) are colouring agents for use in cosmetic products. These colourants may contain chromium (VI), which cause skin allergies through percutaneous adsorption on the skin. Eye shadow is a representative cosmetic product in which significant colourants are used. We analysed the chromium (VI) in the eye shadows by ion chromatography and post column derivatization. We optimize conditions of chromium (VI) analysis in eye shadows. During the pretreatment procedure, there are no exchange of chromium (III) to chromium (VI). This method has a limit of quantification for chromium (VI) of 1.0 μg l−1, recovery rate of 100 ± 3% and analysis time less than 10 min. This result is 300 times more sensitive than the high‐performance liquid chromatography method. We applied the optimized method to analyse 22 eye shadows and 6 colouring agents. 2 out of 22 of the products contained more than 5 mg l−1. In our previous work, 5 mg l−1 of Cr represented a threshold level. There was much more Cr(VI) in the colouring agents. The Cr(VI) in one of the colouring agents was 97.6 mg l−1.

Determination of 19 Preservatives in Various Matrices by High-Performance Liquid Chromatography

A simple and sensitive high-performance liquid chromatography (HPLC) method was developed for the determination of 19 preservatives in cosmetic matrices. The composition of the mobile phase was optimized as a gradient to achieve a lower detection limit when compared to previously validated methods, and sample preparation conditions were investigated to optimize separation of the 19 preservatives. A C18 column was used with methanol, 0.05 mol/L ammonium acetate buffer, and water as the mobile phase under gradient elution conditions. Preservatives in cosmetics were extracted with 70% methanol using an ultrasonicator, after which they were analyzed with an HPLC-photodiode array detector. All preservatives were separated within 55 min. The recoveries ranged from 94.9% to 102.8%, with relative standard deviations of less than 3.2% and no correlation coefficients lower than 0.9986. Additionally, the developed method has a low detection limit, which makes it possible to analyze trace levels of compounds in various cosmetic and ingredient matrices.