359 CHOLINE PROLINE IONIC LIQUID-FUNCTIONALIZED O 4 @SIO 2 FE3FE 43 2 Table I Linear Relati o n ship and Detection Limit Parameter Allura red Linear regression equation S = 4485152c + 240565 Linear range (μg/mL) 0.02–5.0 Correlation coeffi cient (r2) 0.9997 Limit of detection (ng/mL) 9.0 RSD (%) 3.8 14 times, and the extraction effi ciency was lower than 85.0% after being eluted 14 times, which proved that the material can be reused. ANALYTICAL APPLICATION The HPLC chro matogram of allura red standard solution (curve a) and samples before and after extraction (curve b,c) are shown in Figure 13. From Figure 13, the retention time (tR) values for allura red were 11.2 min, and the concentration of the allura red was sig- nifi cantly increased after extraction. Linear relationship and detection li mit. The linear equation, linear correla tion coeffi cient, linear range, relative standard deviation, and detection limit of the method in this article are listed in Table I. Comparison with other methods. The d eveloped method was compared w ith other methods reported in the literature for extraction and determination of allura red (Table II). From Table 2, it can be seen that this method has a wide linear range, low detection of limit, and short extraction time. Real sample analysis. To evaluate th e applicability of th e proposed method, two commer- cial lipsticks were extracted using the method and analyzed by HPLC. The analysis re- sults are shown in Table III. From Table 3, it can be known that allura red was measured in one of the lipstick samples, and the content of allura red in the lipstick was 16.78 mg/ kg. The recovery rate of allura red was 88.05–104.26%, which proved that the method can be used to determine the content of allura red in lipstick. Table II Comparison of Methods for Determination of Allura Red Method Extraction agent Linear range (μg/mL) Detection limit (ng/mL) Extraction time (min) Reference MSPE-LC-MS NH2-LDC-MP 0.05–5.0 9.0 - (14) M-dSPE-LC-MS MSPD 0.005–1.0 1.0 - (15) MSPE-HPLC Fe3O4-NH2@GO 0.005–1.5 2.0 15 (16) CSPE-UV T-1180 0.4–8.0 1.0 120 (17) CPE-UV Mixed micelles 0.02–1.4 8.0 50 (18) MSPE-HPLC Fe3O4@SiO2@IL 0.02–5.0 9.0 5 This work

360 JOURNAL OF COSMETIC SCIENCE CONCLUSION In this work, an MSPE met hod was dev eloped for pre-concentration of allura red for de- termination by HPLC. The sorbent was prepared by functionalizing choline proline ionic liquid on Fe3O4@SiO2. The method had simple operation steps, short extraction process time, and high extraction effi ciency. This method was used to determine the content of allura red in lipsticks, with high sensitivity and good accuracy. ACKNOWLEDGMENTS The authors acknowle dge the fi nancia l support from the National Natural Science Foun- dation of China (21375117) and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. REFERENCES (1) Y. P. Xian, Y. L. Wu , X. D. Guo , Y. J. Lu, H. Y. Luo, D. H. Luo, and Y. G. Chen, Simultaneous deter- mination of 11 restricted dyes in cosmetics by ultra high-performance liquid chromatography/tandem mass spectrometry, Anal. Methods, 5, 1965–1974 (2013). (2) A. Ostovan, H. Asadollahzadeh, a nd M. Ghaedi, Ultrasonically synthesis of Mn- and Cu-@ZnS-NPs- AC based ultrasound assisted extraction procedure and validation of a spectrophotometric method for a rapid preconcentration of allura red AC (E129) in food and water samples, Ultrason Sonochem., 43, 52–60 (2018). (3) A. Bordagaray, R. Garcia-Arrona , M. Vidal, and M. Ostra, Determination of food colorants in a wide variety of food matrices by microemulsion electrokinetic capillary chromatography. Considerations on the found concentrations and regulated consumption limits, Food Chem., 262, 139–133 (2018). (4) W. B. Chai, H. J. Wang, Y. Zhan g , and GS. Ding, Preparation of polydopamine-coated magnetic nanoparticles for dispersive solid-phase extraction of water-soluble synthetic colorants in beverage sam- ples with HPLC analysis, Talanta, 149, 13–20 (2016). (5) S. M. Majidi and M. R. Hadjmoh am madi. Alcohol-based deep eutectic solvent as a carrier of SiO2@ Fe3O4 for the development of magneticdispersive micro-solid-phase extraction method: application for the preconcentration and determination of morin in apple and grape juices, diluted and acidic extract of dried onion and green tea infusion samples, J. Separ. Sci., 42, 2842–2850 (2019). (6) F. Subhan, S. Aslam, Z. F. Yan, M. Khan, U. J. Etim, and M. Naeem, Effective adsorptive performance of Fe3O4@SiO2 core shell spheres for methylene blue: kinetics, isotherm and mechanism, J. Porous Ma- ter., 26, 1465–1474 (2019). (7) I. A. Lawal, M. Klink, P. Ndung u , and B. Moodley, Brief bibliometric analysis of “ionic liquid” applica- tions and its review as a substitute for common adsorbent modifi er for the adsorption of organic pollut- ants, Environ. Res., 175, 34–51 (2019). (8) R. Wo, Q. L. Li, C. Zhu, Y. Zha n g, G. F. Qiao, K. Y. Lei, P. Du, and W. Jiang, Preparation and charac- terization of functionalized metal-organic frameworks with core/shell magnetic particles (Fe3O4@ Table III Analytical Results of Allura Red in Real Sample Sample Added (mg/kg) Found (mg/kg) Recovery (%) RSD (%) Lipstick (I) 0.00 16.78 / 3.4 7.50 23.38 88.05 2.7 15.00 30.79 93.40 1.2 Lipstick (II) 0.00 ND / / 7.50 7.07 94.27 3.8 15.00 15.64 104.26 2.1