Pattamaporn Hemwech¹, Apinya Obma ¹, Sasinun Detsangiamsak ¹, Supa Wirasate ^2,3,4, Prapin Wilairat⁵, Rattikan Chantiwas¹

¹Department of Chemistry and Centre of Excellence for Innovationin Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRSTLabs), Faculty of Science, Mahidol University, Bangkok, Thailand
²Department of Chemistry, Faculty of Science, Mahidol University, Bangkok, Thailand ³Centre for Surface Science and Engineering, Faculty of Science, Mahidol University, Nakhorn Pathom, Thailand
⁴Rubber Technology Research Centre, Faculty of Science, Mahidol University, Nakhorn Pathom, Thailand
⁵Analytical Sciences and National Doping Test Institute, Mahidol University, Bangkok, Thailand

Correspondence Rattikan Chantiwas, Department of Chemistry and Centre of Excellence for Innovation in Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs), Faculty of Science, Mahidol University, RamaVI Rd, Bangkok 10400, Thailand. Email: rattikan.cha@mahidol.ac.th; rattikan.cha@mahidol.edu

Abstract:

Introduction: Phytochemical analysis of phenolic acids and flavonols poses a challenge, necessitating the development of an efficient separation method. This facilitates the quantification of these compounds, yielding valuable insights into their benefits.

Objective: To develop a highly effective separation of phenolic acids and flavonols by capillary electrophoresis and ultraviolet (UV) detection through the modification of the capillary surface using 3-aminopropyltriethoxysilane (APTES) at millimolar concentrations.

Methods: The capillary surface is modified with 0.36 mM-APTES solution. The electrolyte is 20.0 mM borate buffer (pH 9.0). Separation performance (plate number N, resolution Rs), stability, and reproducibility of the coating procedure are evaluated using the analysis of phenolic acids, rutin and quercetin.

Results: The modified capillary provided efficient separation with plate numbers N 2 1.0 x 10⁴ m^-1 and resolution R_s 2 0.8 for all pairs of adjacent peaks of the separation of five selected phenolic acids, rutin, quercetin, caffeine and methylparaben (as internal standard). The precisions of the relative migration times for 17 consecutive analyses of samples over 3 h were 1% relative standard deviation (RSD) for rutin and 7% RSD for quercetin. The analysis of rutin and quercetin in 12 dietary supplement product samples only required a simple dilution step for sample preparation.

Conclusion: A straightforward modification technique utilising millimolar concentrations of APTES resulted in highly efficient separation of phenolic acids, rutin and quercetin, accompanied by high precision and surface stability. The modified capillary proved successful in analysing rutin and quercetin content in dietary supplements.

KEYWORDS

aminosilane surface modification, cathodic EOF, dietary supplement products, millimolar APTES concentration, phenolic acids and flavonols

Reference:

P. Hemwech, A. Obma, S. Detsangiamsak, S. Wirasate, P. Wilairat, R. Chantiwas, Capillary surface modification using millimolar levels of aminosilane reagent for highly efficient separation of phenolic acids and flavonols by capillary electrophoresis with UV detection, Phytochemical Analysis  (2023). doi: 10.1002/pca.3250