Comparison of Fast Gas Chromatography-Surface Acoustic Wave Sensor (FGC-SAW) and Capillary GC-MS for Determining Strawberry and Orange Juice Volatiles

摘要

Fast gas chromatography with surface acoustic wave detection (FGC-SAW) is a new instrumental approach which employs a polymer based volatile trap coupled to a short (1 m) capillary column and a single quartz SAW detector. Typically FGC-SAW headspace volatile analyses take less than 1 min, whereas a typical GC-MS run will take 30-60 min. The tradeoff for such rapid analysis is less chromatographic resolution but the resolution is often adequate for major components. For strawberries, 19 peaks were observed in 20 sec with the FGC-SAW and 80 peaks in 43 min for the GC-MS. For orange juice, 15 peaks were observed in 18 sec with the FGC-SAW and 60 peaks in 43 min for the GC-MS. The entire single analysis time for headspace sampling, GC analysis and instrumental recycling was 51 sec for strawberry and 46 sec for orange juice. Matching retention index values of standards, the major volatiles in strawberry using FGC-SAW were identified as esters, whereas terpenes and esters were the major volatiles identified in orange juice. The identifications were confirmed using GC retention index values and MS fragmentation patterns of standards. Although the chromatographic resolution of fruit volatiles from FGC-SAW was inferior to GC-MS, the usefulness of the data to distinguish strawberry varieties and orange juice quality was surprisingly equivalent. When GC-MS and FGC-SAW chromatographic data from identical samples were analyzed using principle component analysis, PCA, both could clearly differentiate 10 strawberry cultivars as well as between fresh and storage abused orange juice from concentrate.