Capillary Electrophoresis Method for 20 Polyphenols Separation in Propolis and Plant Extracts

In this work, a simple, reliable and fast capillary electrophoresis method was developed and partially validated for simultaneous detection of 20 polyphenolic compounds (presumed to be found in propolis and plant extracts) in less than 27 min. The best results were obtained using 45 mM tetraborate buffer with 0.9 mM sodium dodecyl sulfate (pH = 9.35) as a background electrolyte. The polyphenolic compound order of elution was the following: resveratrol, pinostrobin, acacetin, chrysin, rutin, naringenin, isoquercitrin, umbelliferone, cinnamic acid, chlorogenic acid, galangin, sinapic acid, syringic acid, ferulic acid, kaempferol, luteolin, coumaric acid, quercetin, rosmarinic acid and caffeic acid. Linearity ranges used for compound quantification were satisfactory, presenting correlation coefficients between 0.997 and 0.999 for all 20 compounds. The method showed good performance characteristics: detection and quantification limits of 0.02 to 1.75 and 0.07 to 5.77 μg mL−1, respectively. The relative standard deviation values for repeatability did not exceed 4.86 % for intra-day assays and 5.07 % for inter-day assays. The recovery assays presented results between 87.4 and 114. 2 % for Origanum sample and between 85.0 and 111.0 % for propolis sample. The results obtained from the analysis of samples are in good correlation with literature data and bring new information about less studied samples such us aqueous Romanian propolis extracts and ethanolic Mentha aquatica extract.