SIMULTANEOUS DETERMINATION OF MONOCAFFEOYLQUINIC ACIDS AND CAFFEINE BY REVERSE-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH ELUENTS BASED ON PROPANOL-2 AND ETHYL ACETATE (REJECTION OF ACETONITRILE)

The purpose of the study is development of conditions for the simultaneous determination of caffeine and three isomers of monocaffeoylquinic acids (esters of caffeic and quinic acids: 3CQA, 4CQA and 5CQA) in coffee using "green" reverse-phase HPLC, in which an expensive and environmentally unfavorable acetonitrile is replaced with ethyl acetate as an organic modifier of mobile phases. An approach which provides comparing the efficiency and selectivity of the substance separation in a wide range of concentrations of organic modifiers of selected eluent systems is proposed. It is shown that the replacement of acetonitrile with propanol-2 or ethyl acetate slightly changes the selectivity of the separation of three isomeric chlorogenic acids, but significantly reduces the relative retention of caffeine due to better solvation of caffeine with an organic modifier. This makes it possible to change the position of caffeine elution relative to chlorogenic acids in a targeted way to avoid coelution of caffeine with other extractive substances by changing the concentration and type of the organic modifier of the mobile phase. Ethyl acetate-based eluents are shown to be convenient for simultaneous determination of caffeine and monocaffeoylquinic acids in conditions of reverse-phase HPLC. The replacement of acetonitrile with ethyl acetate makes it possible to re-extract mainly caffeine and monocaffeoylquimc acids from concentrating cartridges (DIAPAK C18) during sample preparation. More lipophilic extractive substances still remain on the concentrating cartridge, which provides the possibility of using a simple isocratic mode thus reducing the duration of analysis and consumption of the organic modifier of the mobile phase.

1. Naveed М., Hejazi V, Abbas М., et al. Chlorogenic acid (CGA): A pharmacological review and call for further research / Biomed. Pharmacotherapy. 2018. Vol. 97. P 67-74. DOI:10.1016/j.biopha.2017.10.064

2. Lopez-Sanchez R. C, Lara-Diaz V J., Aranda-Gutierrez A., et al. HPLC Method for Quantification of Caffeine and Its Three Major Metabolites inHumanPlasma Using Fetal Bovine Serum Matrix to Evaluate Prenatal Drug Exposure / J. Anal. Methods Chem. 2018. Vol. 2018. 2085059. DOI:10.1155/2018/2085059

3. Cornells M. C. The Impact of Caffeine and Coffee on Human Health / Nutrients. 2019. Vol. 11. P 416. DOI:10.3390/null020416

4. Clifford M. N., Jaganath I. В., Ludwig I. A., Crozier A. Chlorogenic acids and the acyl-quinic acids: discovery, biosynthesis, bioavailability and bioactivity / Nat. Prod. Rep. 2017. Vol. 34. P 1391-1421. DOI:10.1039/C7NP00030H

5. Koseoglu Yilmaz P., Kolak U. SPE-HPLC Determination of Chlorogenic and Phenolic Acids in Coffee / J. Chromatogr. Sci. 2017. Vol. 55. P 712-718. DOI:10.1093/chromsci/bmx025

6. Kremr D., Bajer Т., Bajerova P., et al. Unremitting problems with chlorogenic acid nomenclature: a review / Quim. Nova. 2016. Vol. 39. P 530-533. DOI:10.5935/0100-4042.20160063

7. Fujioka K., Shibamoto T. Chlorogenic acid and caffeine contents in various commercial brewed coffees / Food Chem. 2008. Vol. 106. P 217-221. DOI:10.1016/j.foodchem.2007.05.091

8. Arai K., Terashima H., Aizawa S., et al. Simulteneous determination of trigonelline, caffeine chlorogenic acid and their related compounds in instant coffee samples by HPLC using an acidic mobile phase containing octanesulfonate / Anal. Sci. 2015. Vol. 31. P 831-835. DOI:10.2116/analsci.31.831

9. Jeszka-Skowron M., Sentkowska A., Pyrzynska K., De Peca M. P. Chlorogenic acids, caffeine content and antioxidant properties of green coffee extracts: influence of green coffee bean preparation / Eur. Food Res. Technol. 2016. Vol. 242. P 1403-1409. DOI:10.1007/s00217-016-2643-y

10. Campa C., Doulbeau S., Dussert S., et al. Qualitative relationship between caffeine and chlorogenic acid contents among wild Coffea species / Food Chem. 2005. Vol. 93. P 135-139. DOI:10.1016/j.foodchem.2004.10.015

11. Jeon J.-S., Kim H.-T., Jeong I.-H., et al. Determination of chlorogenic acids and caffeine in homemade brewed coffee prepared under various conditions / J. Chromatogr. B. 2017. Vol. 1064. P 115-123. DOI:10.1016/j.jchromb.2017.08.041

12. Rodrigues N. P., Bragagnolo N. Identification and quantification of bioactive compounds in coffee brews by HPLC - DAD - MSn / J. Food Сотр. Anal. 2013. Vol. 32. P 105-115. DOI:10.1016/j.jfca.2013.09.002

13. Vinson J. A., Chen X., Garver D. D. Determination of Total Chlorogenic Acids in Commercial Green Coffee Extracts / Med. Food. 2019. Vol. 22. P 314-320. DOI:10.1089/jmf.2018.0039

14. Sychev K., Styskin I. HPLC Separation of Tea and Coffe Compounds in HILIC mode of the VEZHKH regime / Analitika. 2012. Vol. 5. N 4. P 56-61 [in Russian].

15. Yabre M., Ferey L., Touridomon Some I., Gaudin K. Greening Reversed-Phase Liquid Chromatography Methods Using Alternative Solvents for Pharmaceutical Analysis / Molecules. 2018. Vol. 23. 1065. DOI:10.3390/molecules23051065

16. Dorsey J. G., Dill K. A. The Molecular Mechanism of Retention in Reversed-Phase Liquid Chromatography / Chem. Rev 1989. Vol. 89. P 331-346. DOI:10.1021/cr00092a005

17. Deineka V I., Deineka L. A., Saenko I. I., Chulkov A. N. A Float Mechanism of Retention in Reversed-Phase Chromatography / Russ. J. Phys. Chem. A. 2015. Vol. 89. P 1300-1304. DOI:10.1134/S0036024415070079

18. Deineka V. I., Oleinits E. Y, Blinova I. P., Deineka L. A. Selectivity of the Separation of Isomeric Chlorogenic Acids under the Conditions of Reversed-Phase HPLC / J. Anal. Chem. 2019. Vol. 74. P 778-783. DOI:10.1134/S1061934819080057

19. Murakami F. Retention behavior of benzene derivatives on bonded reversed-phase columns / J. Chromatogr. 1979. Vol. 178. N 2. P 393-399. DOI:10.1016/S0021-9673(00)92497-X

20. Deineka V I. Chromatographic separation map and incremental relationships in the method of relative analysis of retention under HPLC conditions / Russ. J. Phys. Chem. 2006. Vol. 80. P 429-434. DOI:10.1134/S0036024406030204