3471 J. Cosmet. Sci., 72, 1–15 (July/August 2021)2021) Choline Proline Ionic Liquid-Functionalized Fe 3 O 4 @SiO 2 Nanoparticle Magnetic Solid Phase Extraction Coupled with High-Performance Liquid Chromatography for Analysis of Allura Red in Lipstick Sample QI LI, QING GAO, WEI LIU, and XIASHI ZHU , College of Guangling, Yangzhou University, Yangzhou University, Yangzhou 225002, PR China (X.Z.) College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou University, Yangzhou 225002, PR China (Q.L., Q.G., W.L., X.Z.) Accepted for publication April 2, 2021. Synopsis A separation/analysis of allura red based on magnetic solid-phase extraction–high-performance liquid chromatography was developed. The extractant was prepared by functionalizing choline proline ionic liquid on Fe3O4@SiO2(Fe3O4@SiO2@[Ch][Pro]). Infl uences of experimental variables including extraction condition (material amount, pH, time, temperature, ionic strength, and sample volume) and elution conditions (eluent selection, amount, time) were evaluated. Under the optimal conditions, good linear calibration curves were obtained in the range of 0.02–5.0 μg/mL, and limits of detection was 9.0 ng/mL. The proposed method was successfully applied for the determination of allura red in lipstick sample. I NTRODUCTION Dyes are often used as colorants in foods, medicines, and cosmetics. Cosmetics have been widely welcomed by consumers in recent years. Lipsticks can change the lip color this intuitive feeling is more attractive to consumers (1). Allura red is a dye commonly used in lipsticks as a synthetic sulfonated azo red dye (Figure 1), compared with natu- ral pigments, it has the advantages of good stability and low cost, but the molecular structure contains an azo group (-N = N-), which may cause adverse effects on human health (2). And the dye in lipstick is easy to be eaten by consumers, and excessive in- take of allura red can cause carcinogenic diseases, allergies, multiple sclerosis, and brain damage (3). Therefore, it is necessary to determine the allura red of lipstick. At present, the commonly used methods for determining allura red are UV spectrophotometry (2) Address all correspondence to Xiashi Zhu at xszhu@yzu.edu.cn or zhuxiashi@sina.com. 347–361

348 JOURNAL OF COSMETIC SCIENCE 2 and liquid chromatography (4). Because the matrix in lipsticks is complex and can- not be measured directly, it is important to develop effective sample pre-preparation methods. Magnetic solid phase extraction (MSPE) is an extraction technology based on mag- netic or magnetizable materials as solid absorbents. In the MSPE procedure, the mag- netic adsorbent is dispersed in the sample solution to adsorb the analyte, and then, the analyte is collected by an external magnetic fi eld, which greatly simplifi es the tradi- tional solid phase extraction and improves the extraction effi ciency (5). MSPE is mainly based on the surface modifi cation of Fe3O4 nanoparticles SiO2 is often used to modify Fe3O4 nanoparticles, and because of its high porosity and high surface area, it has a good adsorption of target analytes (6). However, the material also has its limitations unlike chemical adsorption process, physical adsorption is limited in terms of porosity and surface area, especially the blockage of oil and organic macromolecules in the real sample, leading to a decrease in the adsorption rate of the analyte (7). Therefore, it has become a research focus in recent years to functionalize Fe3O4@SiO2 nanoparticles to improve the adsorption. Some adsorbents such as Fe3O4@SiO2@MOFs (8), Fe3O4@ SiO2@ILs (9), and Fe3O4@SiO2@GO (10) are used in the separation analysis of target analytes. Choline amino acid ionic liquids ([Ch][AA] have attracted attention in re- cent years because of their advantages of nontoxicity, good biocompatibility, and natu- ral degradation. The positively charged choline cations in its structure showed a good electrostatic interaction with anionic target analytes. However, there are few reports on the modifi cation of Fe3O4@SiO2 nanoparticles with choline amino acid ionic liquids. The aim of this work was to develop a method which was based on Fe3O4@SiO2@[Ch] [Pro], followed by magnetic solid-phase extraction–high-performance liquid chromatog- raphy to determine allura red in real samples. Fe3O4@SiO2@[Ch][Pro] was selected as an extractant, which was with good biological affi nity and environmentally friendly, and no organic solvent that was of great importance from the perspective of green chemistry was consumed in the entire extraction process. Figure 1. Structure of allura red.