Validated application of a new high-performance liquid chromatographic method for the determination of selected flavonoids and phenolic acids in human plasma using electrochemical detection.

We developed a sensitive method for determination of 23 flavonoids and phenolic acids, which represent phenolic acids and five subclasses of flavonoids. Plasma samples were extracted with selective solid-phase-extraction columns and separated by RP-high-performance liquid chromatography (HPLC). For detection an electrochemical detector was used. Identification and test of purity were carried out via retention times and spectra analyses. Limits of detection varied from 1.45 to 22.27 nmol/l. Recovery varied from 81% to 106%. Reproducibility for all analytes was below 10% (coefficient of variation, CV (%)) and ranged between 3.1% and 9.8%. This method can be applied to samples from interventional studies as well as observational studies.