CAFFEINE IN HAIR-CARE AND ANTICELLULITE COSMETICS 261 preparation of anticellulite gels, shampoos, and hair balsam, clear and nonviscous solu- tions were obtained. Potentially interfering compounds were removed, and the caffeine content was determined with satisfactory accuracy and precision. The selection of the cartridge sorbent is of great importance to obtain high extraction yields. Surprisingly, more polar octyl modifi ed silica phase gave higher recoveries only for hair balsam, whereas for gels and shampoos, the most suitable sorbent was a polystyrene– divinylbenzene copolymer. These indicate that the choice of the cartridge sorbent de- pends not only on physical and chemical characteristics of the analyte but also depends on the sample matrix. Thus, different cartridges must be used for caffeine extraction from different cosmetic products. This article contributes to the development and application of SPE in the analysis of cos- metic products. The SPE procedure optimization showed the importance of screening the performance of a range of cartridge types when applying SPE techniques to samples of the complexity often encountered in personal care products. ACKNOWLEDGMENTS This research was fi nancially supported by the Faculty of Medicine, University of Niš, internal scientifi c project (Grant No 2, 11-14629-4/2) and by the Ministry of Education, Science, and Technological Development of the Republic of Serbia (Grant TR 31060). REFERENCES (1) A. Herman and A. P. Herman, Caffeine’s mechanisms of action and its cosmetic use, Skin Pharmacol. Physiol., 26, 8–14 (2013). (2) D. Hexsel, C. Orlandi, and D. Zechmeister do Prado, Botanical extracts used in the treatment of cel- lulite, Dermatol. Surg., 31, 866–872 (2005). (3) D. Hexsel and M. Soirefmann, Cosmeceuticals for cellulite, Semin. Cutan. Med. Surg., 30, 167–170 (2011). (4) M. E. Sawaya and V. H. Price, Different levels of 5α-reductase type I and II, aromatase, and androgen receptor in hair follicles of women and men with androgenetic alopecia, J. Invest. Dermatol., 109, 296– 300 (1997). ( 5) M. Jafari and A. Rabbani, Studies on the mechanism of caffeine action in alveolar macrophages: caffeine elevates cyclic adenosine monophosphate level and prostaglandin synthesis, Metabolism, 53, 687–692 (2004). ( 6) T. W. Fischer, U. C. Hipler, and P. Elsner, Effect of caffeine and testosterone on the proliferation of hu- man hair follicles in vitro, Int. J. Dermatol., 46, 27–35 (2007). ( 7) X. Liu, J. E. Grice, J. Lademann, N. Otberg, S. Trauer, A. Patzelt, and M. S. Roberts, Hair follicles contribute signifi cantly to penetration through human skin only at times soon after application as a solvent deposited solid in man, Br. J. Clin. Pharmacol., 72, 768–774 (2011). ( 8) N. Otberg, A. Patzelt, U. Rasulev, T. Hagemeister, M. Linscheid, R. Sinkgraven, W. Sterry, and J. Lademann, The role of hair follicles in the percutaneous absorption of caffeine, Br. J. Clin. Pharmacol., 65, 488–492 (2008). ( 9) J. L. Temple, Ch. Bernard, S. E. Lipshultz, J. D. Czachor, J. A. Westphal, and M. A. Mestre, The safety of ingested caffeine: a comprehensive review, Front. Psychiatry, 8, 80 (2017). ( 10) FDA (2000), Thigh Creams (Cellulite Creams), accessed February 14, 2020, https://www.fda.gov/cosmet- ics/cosmetic-products/thigh-creams-cellulite-creams. ( 11) R. Injac, B. Srdjenovic, M. Prijatelj, M. Boskovic, K. Karljikovic-Rajic, and B. Strukelj, Determination of caffeine and associated compounds in food, beverages, natural products, pharmaceuticals, and cosmet- ics by micellar electrokinetic capillary chromatography, J. Chromatogr. Sci., 46, 137–143 (2008).

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