Determination of flavonoids in plant material by HPLC with diode-array andelectro-array detections

A high-performance liquid chromatographic (HPLC) method with in-line connec ted diode-array (DAD) and electro-array (EC) detection to identify and quan tify 17 flavonoids in plant-derived foods is described. Catechins were extr acted from the samples using ethyl acetate, and quantification of these com pounds was performed with the EC detector. Other flavonoids were quantified with DAD after acid hydrolysis. The methods developed were effective for t he determination of catechins and other flavonoids in plant-derived foods. Responses of the detection systems were linear within the range evaluated, 20-200 ng/injection (DAD) and 20-100 ng/injection (EC), with correlation co efficients exceeding 0.999. Coefficient of variation was under 10.5%, and r ecoveries of flavonoids ranged from 70 to 124%. Purity of the flavonoid pea ks was confirmed by combining the spectral and voltammetric data.