This study describes a method for the determination of 5-hydroxymethyl-2-furfural (HMF) and 2-furfural (F) in oils. The method entails liquid-liquid extraction and reversed-phase liquid chromatography. Spiked hazelnut oil was used to test the accuracy and reliability of the method. Furan compounds were extracted from oil using 70% methanol. Mean recoveries were 97 +/- 2% and 99 +/- 1% for HMF and F, respectively. To investigate the presence of HMF and F in oils, seven oily nuts and seeds were roasted at 180 degrees C for 30 min. Different oils were found to contain HMF and F ranging from 0.8 to 13.8 and 1.4 to 8.7 mg/kg, respectively. Increasing solvent polarity also increased the rate of HMF transferred to the oil. Spectral analyses of the 70% methanol extracts indicated that absorbance at 285 nm may be used to monitor the accumulation of furan compounds in oil phase during the roasting process of nuts. (C) 2010 Elsevier Ltd. All rights reserved.