Determination of selected antioxidants in Melissae herba by isotachophoresis and capillary zone electrophoresis in the column-coupling configuration

A method utilising isotachophoresis and capillary zone electrophoresis in the column coupling configuration with UV detection at 320 nm was developed for separation and determination of five phenolic acids (rosmarinic, p-coumaric, ferulic, caffeic and chlorogenic) and flavonoid quercitrin in a methanolic extract of Melissae herba. The proposed method has been validated with correlation coefficients from 0.9842 to 0.9988, RSD values between 0.39% and 0.83% for migration times and between 0.40% and 2.05% for peak areas.