Optimization and application of headspace liquid-phase microextraction coupled with gas chromatography-mass spectrometry for determination of furanic compounds in coffee using response surface methodology

A simple and accurate method for determination of furanic compounds in coffee samples using headspace liquid-phase microextraction (HS-LPME) combined with gas chromatography-mass spectrometry (GC/MS) was developed and validated. In addition to furan, other furanic compounds such as 2-methylfuran, 2,5-dimethylfuran, 2-vinyl furan, 2-(methoxymethyl) furan and furfural were also determined. The effective parameters in HS-LPME process, including ionic strength, stirring rate, temperature and time of extraction process were optimized using response surface methodology (RSM) based on central composite design. The results of optimization study showed that stirring rate, temperature and time of extraction parameters have positive effect on the efficiency of microextraction process but the effect of salt addition on response was negative. The optimal extraction conditions using a quadratic model were: stirring rate 700 rpm, extraction temperature 43 C, extraction time 15 min and without salt addition. The calibration curves showed good linearity (R-2>0.99) for all the furanic compounds in the range of 0.2-400 ng mI(-1). Repeatability varied from 4.2% to 9.5%. The method accuracy was acceptable with recoveries ranging from 79.6% to 102%. Good enrichment factors were obtained e.g. 1270 for furan. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.02 to 10 ng g(-1) and 0.06 to 39 ng g(-1), respectively. The comparison of validated method with two other methods for furan analysis showed comparable merit figures and proved the applicability of HS-LPME followed by GC/MS for extraction and determination of furanic compounds in coffee samples. (C) 2012 Elsevier B.V. All rights reserved.