Capillary surface modification using millimolar levels of aminosilane reagent for highly efficient separation of phenolic acids and flavonols by capillary electrophoresis with UV detection.

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 R ), 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 ≥ 1.0 × 10  m and resolution R ≥ 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.