Analytical Determination of Ochratoxin A in Brewed and Green Coffee Beans by High-Performance Liquid Chromatography - Fluorescent Detector Method

Coffee contamination by Ochratoxin A (OTA) is becoming the main global emerging threat to its quality. The main objective of this study was to determine the levels of Ochratoxin A in coffee beans and brewed coffee samples. Twenty samples of coffee beans and brewed were each randomly collected from coffee stores and street coffee vendors, respectively. The levels of OTA in the coffee samples were determined using High-Performance Liquid Chromatography (HPLC) with a Fluorescence Detector (FD). The calibration curve for the analyte was linear in the concentration range of 1 mu g/L mu g/L- 15 mu g/L mu g/L (R2 2 = 0.997) and 1 mu g/kg mu g/kg- 15 mu g/kg for green coffee beans (R-2 = 0.998). The mean concentration of OTA in brewed and coffee beans composite samples was found to be 1.92 mu g/L +/- 0.07 mu g/L (n=10) and 1.52 mu g/kg +/- 0.28 mu g/kg (n=10), respectively. The Limit of Detection (LOD) and Limit of Quantification (LOQ) of the method calculated from the calibration curves were 0.76 mu g/kg, 0.69 mu g/L and 2.31 mu g/kg, 2.07 mu g/kg for green coffee bean and brewed samples, respectively. The precision of the method expressed in percent Relative Standard Deviations (RSD) of the recoveries was less than 20 % and the mean recovery was 76.28 % - 106.57%. Even though the concentrations of OTA in studied samples didn't exceed the maximum residue limit set by international organizations, a positive result signals coffee pollution by these toxic substances and careful monitoring is essential to improve the quality of coffee and halt its health and economic effects.