Identification and quantitative determination of 2-acetyl-1-pyrroline using GC-TOF MS combined with HS and HS-SPME pretreatment

2-Acetyl-1-pyrroline (2-AP) was recognized as the key characteristic volatile in aromatic rice. In this paper, two precise and rapid methods for quantitative determination of 2-AP by headspace-gas chromatography-time-of-flight mass spectrometry (HS-GC-TOF MS) and headspace-solid phase micro-extraction-gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC-TOF MS) have been presented and compared. Chromatograms of 2-AP and internal standard (2-methyl-3-heptanone) in samples were extracted by accurate masses, and the response ratios of 2-AP to internal standard were used for constructing matrix-matched standard curve with the blanks deducted. Pretreatment conditions such as temperature and extractant amount were optimized. Linear ranges of two methods were 1-150 ng g(-1) with linear correlation coefficients (r) of 0.9998 and 0.9997, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) of HS-GC-TOF MS method were 0.68 ng g(-1) and 2.27 ng g(-1). LOD and LOQ of HS-SPME-GC-TOF MS method were 0.46 ng g(-1) and 1.50 ng g(-1), and could be reduced to 0.02 ng g(-1) and 0.06 ng g(-1), respectively, in the case of splitless mode. At spiking level of 100 ng g(-1), recoveries were 94.19-116.00% and 95.57-107.49% for HS-GC-TOF MS method and HS-SPME-GC-TOF MS method, respectively.