Since its early days, conventional

Since its early days, conventional gas chromatography (1D-GC) has been recognised as a tool offering higher peak capacities than other chromatographic techniques. Over the years, dramatic progress has been made and, today, state-of-the-art 1D-GC on capillary columns can, typically, separate some 100–150 peaks in one run However its resolution power is insufficient to fully resolve each individual constituent in real complex samples, ranging from oils,petrochemicals,environmental samples, cigarette smoke, and food matrices, without sacrificing analysis time. It has been reported by Berger that, in an 11 h experiment, the use of a 400 m column presented a resolution of 1.3 million theoretical plates, which was far from sufficient for the total separation of a fuel sample
Introduced by Philips and coworkers (Liu & Phillips, 1991), comprehensive two-dimensional gas chromatography (GC  GC) has greatly enhanced peak capacity, without significantly extending analysis time, over conventional 1D-GC
In recent years, food analysis has been revolutionised due to intense application of GC  GC to highly complex matrices such as coffee, wine, beer, fruit aromas and honey, either for fingerprinting, classification or tracing geographical origins

tion than is offered by a 1D profile, resulting in the perfect combination. Also detectability and separation power has been enhanced, therefore compounds never reported in the literature before, have been discovered and possibly classification protocols must be updated. Due to multivariate data assessment tools classification procedures have become even more accurate and less subjective Even more developments have been reported in
quantitative analysis. The adulteration of complex mixtures, like gasoline, for instance, has been detected and quantified
Also it has been reported by Ribeiro, Augusto, Salva, Thomaziello, and Ferreira
that the chromatographic profile of volatile and semi-volatile fractions of Brazilian Arabica roasted coffee could be used to predict sensory properties, an important attribute of coffee quality.These latter features reveal several novel opportunities in application of food chemistry, especially in matters of detecting and quantifying adulteration, certification protocols (quality labels,protected designation of origin, protected geographical indication and traditional specialty guarantees) and sensory properties,increasing significantly the market values of the products.
Schmarr and Stanimirova reported classification procedures offruit aroma and honey through static headspace extraction (HS) However,as attractive as this sounds, solid phase microextraction (SPME) presents several advantages, such as concentration prior to analysis, selectivity, and it is a solvent-free technique. During headspace equilibrium, usually obtained in aqueous solution with heating, species not present in the original sample are formed, so called
artifacts. An important class of artifacts is known to be products of the well established Maillard reaction, resulting from the reaction between an amino acid and a reducing sugar, usually requiring heating. In 1988 reported the presence
of 5-(hydroxymethyl)furan-2-carbaldehyde (also denominated hydroxymethylfurfural) during honey processing at
elevated temperatures, and since then this marker has been correlated to improper thermal exposure. In 2001 Tosi, Chiappini, and Ré (2002) reported the effect of honey thermal treatment on hydroxymethylfurfural (HMF) content suggesting that the production of HMF was strongly influenced by the temperature, following a pseudo first order kinetic model. These implications suggest that improper handling of the sample during HS extraction can lead to erroneous results, either for fingerprinting or classification goals.