Potential of the Reversed-Inject Differential Flow Modulator for Comprehensive Two-dimensional Gas Chromatography in the Profiling and Fingerprinting of volatiles from complex food samples

Comprehensive two-dimensional gas chromatography (GC×GC) coupled with Mass Spectrometry (MS) is one of the most powerful analytical platforms now available for the detailed profiling (identification and quantitation) of medium-to-high complexity food samples [1]. Compared to one-dimensional systems, it offers remarkable separation power and unmatched peak capacity, rationalized 2D separation patterns that are distinctive sample fingerprints for classification and authentication [2-5]. Thermal modulated GC×GC platforms enable comprehensive investigations required in food “omics” thanks also to their hyphenation with mass spectrometric detection, automated sample-preparation, olfactory detection and suitable data elaboration approaches. The introduction on the market of GC×GC platforms implementing differential flow-modulation, based on the design proposed by Seeley et al. [6], has opened a new perspective for complex samples analysis (profiling and fingerprinting). Lower operational costs, relative ease of use and simple maintenance make these platforms attractive also for routine operations. This study investigates and critically discusses the potential of a “second generation” design of differential flow modulation that adopts a reverse fill/flush injection dynamic for profiling and fingerprinting of medium-to-highly complex fractions of volatiles from different food samples. In particular, a parallel dual-secondary column dual-detection configuration was tested; this system has shown to improve the information potential also with thermally modulated GC×GC (MS identification reliability and accurate FID quantitation). This contribution presents chromatographic performance parameters and the most effective systems for quantitative profiling of flavoring agents (Mentha spp. essential oils) and fingerprinting of complex fractions from roasted samples (hazelnuts and cocoa). Experimental results show that a careful optimization of both column dimensions and system configurations yields accurate and reliable results compatible with routine quality controls and high throughput screenings. 1. Cordero C, Kiefl J, Schieberle P, Reichenbach SE, Bicchi C. Analytical and Bioanalytical Chemistry. 2015;407(1):169-91. 2. Nicolotti L, Cordero C, Bressanello D, Cagliero C, Liberto E, Magagna F, et al. Journal of Chromatography A. 2014;1360:264-74. 3. Purcaro G, Cordero C, Liberto E, Bicchi C, Conte LS. T. Journal of Chromatography A. 2014;1334:101-11. 4. Cordero C, Cagliero C, Liberto E, Nicolotti L, Rubiolo P, Sgorbini B, et al. Journal of Chromatography A. 2013;1318:1-11. 5. Nicolotti L, Cordero C, Cagliero C, Liberto E, Sgorbini B, Rubiolo P, et al. Anal Chim Acta. 2013;798:115-25. 6. J. V. Seeley, N. J. Micyus, J. D. McCurry, S. K. Seeley, Am. Lab. 38 (2006) 24−26