Ochratoxin A in roasted coffee marketed in Czech Republic: determination by liquid chromatography and fluorescence detection

This study dealt with determination of ochratoxin A (OTA) in roasted coffee by ultra-performance liquid chromatography and fluorescence detection (UPLC-FLD). Coffee features characteristic sensory properties, contains a wide range of beneficial substances and is among the most sold commodities worldwide. UPLC-FLD method for determination of OTA in ground roasted coffee was optimized and validated. A calibration curve of good linearity (R2 > 0.999) was obtained for the range of 0.3–10 ng·ml-1, and the limit of detection and limit of quantification for OTA were 0.1 µg·kg-1 and 0.3 µg·kg-1, respectively. The recovery of certified reference material for OTA ranged between 81.3–112.8 % and the relative standard deviation under repeatibility conditions was 11.7 %. The method was applied to the analysis of OTA in coffee obtained from retail stores in Czech Republic. Sixteen samples (29 %) of roasted coffee were positive, containing OTA in the range from 0.31 µg·kg-1 to 1.06 µg·kg-1. None of the samples analysed exceeded the legislative limit according to EU Commission Regulation No. 1881/2006.