Abstract: A gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) method for the precise quantitative and qualitative analysis of 58 volatile components in grape fruits of different varieties using stable isotope labeled internal standard was developed based on the understanding of the mass spectrometric cleavage behavior of special volatile components. The difference in the volatile composition of the tested varieties was explored. After crushing and homogenization, grape samples were extracted by solid phase microextraction (SPME) and analyzed by GC-MS-SIM. The results indicated that this method had good linear relationships within the investigated concentration range with a correlation coefficient (R) greater than 0.995 0 for all analytes expect for isopropanol (equal to 0.967 1). The limits of detection (LODs) for most target compounds were lower than 1.56 μg/kg. The spiked recoveries of only a few volatile components were very low, while those of most volatile components ranged from 60.64% to 129.63% with relative standard deviations (RSDs) less than 19.56%. This method was suitable for qualitative and quantitative analysis of volatile components in grape and other fruits as well as vegetables, with high sensitivity and accuracy. Furthermore, the characteristic volatile components of 12 grape varieties were identified by analyzing the differences in their volatile composition.

Key words: volatile substances; grape; gas chromatography-mass spectrometry; selected ion monitoring; stable isotope labeled internal standard