Determination of ochratoxin A in green coffee beans by solid-phase micro-extraction and liquid chromatography with fluorescence detection

A new method for the determination of Ochratoxin A (OTA) in green coffee beans by solid-phase microextraction (SPME) coupled to liquid chromatography with fluorescence detection (LC-FD) is described for the first time. Coffee samples were extracted by a 5% NaHCO(3) solution, followed by a clean-up step of the extract by chloroform partition. The aqueous extract was then acidified and finally subjected to SPME-LC-FD analysis. The investigated linear range in coffee was 2-32ng/g. Within-day RSD% in coffee spiked at 2 and 32ng/g levels were 3.3 and 2.7, respectively, whereas the between-days RSD% were 4.1 and 3.8, respectively. The limits of detection (LOD) and quantitation (LOQ), calculated at a signal-to-noise ratio of 3 and 10 (noise calculated peak to peak on a blank chromatogram at the OTA retention time), were 0.3 and 2 ng/g, respectively.