Simultaneous Determination of Gallic Acid and Catechins in Banana Peel Extract by Reversed-Phase High Performance Liquid Chromatography

Abstract

     A reversed-phase HPLC method for the simultaneous determination gallic acid, gallocatechin, catechin, epicatechin and epigallocatechin gallate in banana peel extract was developed. The separation was achieved using a reversed-phase (C18) analytical column and an isocratic elution using a mobile phase of acetonitrile-formic acid (15:85 v/v, pH 2.5). The detection wavelength was set at 275 nm. The chromatographic parameters such as peak asymmetry, capacity factor, selectivity factor and resolution factor were determined. Optimization of parameters such as the detection wavelength, the amount of acetonitrile for a mobile phase and the methanol concentration on stability of standard solution was carried out. Under the optimum conditions, the order of elution was gallic acid, gallocatechin, catechin, epicatechin and epigallocatechin gallate, respectively, with the analysis time of 20 min per chromatogram. The validation parameters such as linearity, range, limit of detection, limit of quantitation, selectivity, precision and accuracy, were evaluated. Linear calibration graphs were in range of 0.25-20 mg L^-1 for gallic acid and 0.50-30 mg L^-1 for gallocatechin, catechin, epicatechin and epigallocatechin gallate, respectively. The proposed HPLC method was simple and rapid, and successfully applied to real samples of banana peel (ripe and green) extracts. Acceptable precisions (%RSD) and recoveries (%Rec) were obtained in the ranges of 0.3-5.9 % and 83±1–128±1 %, respectively, by spiking all samples with a mixed standard solution of five analytes. Banana peel extracts contains many phenolic compounds, especially gallic acid, catechin, epicatechin and epigallocatechin gallate.