| Title: | Untargeted and Targeted Fingerprinting of Extra Virgin Olive Oil Volatiles by Comprehensive Two-Dimensional Gas Chromatography with Mass Spectrometry: Challenges in Long-Term Studies |
| Author(s): | Stilo F; Liberto E; Reichenbach SE; Tao Q; Bicchi C; Cordero C; |
| Address: | "Dipartimento di Scienza e Tecnologia del Farmaco , Universita degli Studi di Torino , Turin I-10125 , Italy. Computer Science and Engineering Department , University of Nebraska , Lincoln , Nebraska 68588 , United States. GC Image, LLC , Lincoln , Nebraska 68508 , United States" |
| ISSN/ISBN: | 1520-5118 (Electronic) 0021-8561 (Linking) |
| Abstract: | "Comprehensive two-dimensional gas chromatography coupled with mass spectrometric detection (GC x GC-MS) offers an information-rich basis for effective chemical fingerprinting of food. However, GC x GC-MS yields 2D-peak patterns (i.e., sample 2D fingerprints) whose consistency may be affected by variables related to either the analytical platform or to the experimental parameters adopted for the analysis. This study focuses on the complex volatile fraction of extra-virgin olive oil and addresses 2D-peak patterns variations, including MS signal fluctuations, as they may occur in long-term studies where pedo-climatic, harvest year, or shelf life changes are studied. The 2D-pattern misalignments are forced by changing chromatographic settings and MS acquisition. All procedural steps, preceding pattern recognition by template matching, are analyzed and a rational workflow defined to accurately realign patterns and analytes metadata. Signal-to-noise ratio (SNR) detection threshold, reference spectra extraction, and similarity match factor threshold are critical to avoid false-negative matches. Distance thresholds and polynomial transform parameters are key for effective template matching. In targeted analysis (supervised workflow) with optimized parameters, method accuracy reaches 92.5% (i.e., % of true-positive matches) while for combined untargeted and targeted ( UT) fingerprinting (unsupervised workflow), accuracy reaches 97.9%. Response normalization also is examined, evidencing good performance of multiple internal standard normalization that effectively compensates for discriminations occurring during injection of highly volatile compounds. The resulting workflow is simple, effective, and time efficient" |
| Keywords: | Gas Chromatography-Mass Spectrometry/instrumentation/*methods Olive Oil/*chemistry Time Factors Volatile Organic Compounds/*chemistry combined untargeted and targeted (UT) fingerprinting comprehensive two-dimensional gas chromatography coupled to time-of-; |
| Notes: | "MedlineStilo, Federico Liberto, Erica Reichenbach, Stephen E Tao, Qingping Bicchi, Carlo Cordero, Chiara eng Evaluation Study 2019/04/18 J Agric Food Chem. 2019 May 8; 67(18):5289-5302. doi: 10.1021/acs.jafc.9b01661. Epub 2019 Apr 24" |
