Although comprehensive two-dimensional gas chromatography (GC Â GC) has been on the scene for more than 15 years, it is still generally considered a relatively novel technique and is yet far from being fully established. The revolutionary aspect of GC Â GC, with respect to classical multidimensional chromatography, is that the entire sample is subjected to two distinct analytical separations. The resulting enhanced separating capacity makes this approach a prime choice when GC analysts are challenged with highly complex mixtures. The combination of a third mass spectrometric dimension to a GC Â GC system generates the most powerful analytical tool today for volatile and semi-volatile analytes. The present review is focused on the rather brief, but not scant, history of comprehensive two-dimensional GC-MS: the first experiments were carried out at the end of the 1990s and, since then, the methodology has been increasingly studied and applied. Almost all GC Â GC-MS applications have been carried out by using either a time-of-flight or quadrupole mass analyzer; significant experiments relative to a variety of research fields, as well as advantages and disadvantages of the MS systems employed, are discussed. The principles, practical and theoretical aspects, and the most significant developments of GC Â GC are also described. #

No abstract

This investigation is based on the automated solid phase microextraction GC-MS analysis of the volatile fraction of a variety of coffee bean matrices. Volatile analytes were extracted by headspace (HS)-SPME which was achieved with the support of automated instrumentation. The research was directed towards various important aspects relating to coffee aroma analysis: monitoring of the volatile fraction formation during roasting; chromatographic differentiation of the two main coffee species (Arabica and Robusta) and of a single species from different geographical origins; evaluation of the influence of specific industrial treatments prior to roasting. Reliable peak assignment was carried out through the use of a recently laboratory-constructed "flavour and fragrance" library and a dual-filter MS spectral search procedure. Further emphasis was placed on the automated SPME instrumentation and on its ability to supply highly repeatable chromatographic data.

No abstract

The present paper provides descriptions and critical views of the most significant chromatography-based methods, employed in the field of Citrus essential oils, mainly over the past decade. Both single-column and multidimensional chromatography approaches are reported, with advantages and shortcomings of each method reported. The contribution reports compositions only marginally. For detailed information on the latter issue, the reader is directed to two books, namely Citrus and Citrus oils, referenced in the paper. A great deal of space is devoted to the use of the mass spectrometer, in relation to its potential for separation and identification. The employment of the most powerful chromatography techniques available today, namely comprehensive two-dimensional ones, is also described. Finally, possible future scenarios in the field of Citrus essential oil analysis are anticipated.

This investigation is based on the gas chromatographic analysis of the volatile fraction of Sicilian goat cheese. Volatile analytes were extracted through static headspace solid phase microextraction (HS-SPME) with the support of a modern automatic instrument designed specifically for this sampling procedure. Component identification was carried out by GC-MS and the employment of internal standard compounds. In the preliminary part of this research, different fibres and capillary columns were tested and their effectiveness compared in order to optimize solute extraction and separation. Furthermore, the HS-SPME sampling conditions were properly tuned in order to maximize solute absorption. Evaluations were also made on the SPME instrumentation and its capability to supply reproducible data. The optimized method was applied to the investigation of six goat cheese samples and their aroma profiles were evaluated, leading to the identification of 44 components.

No abstract

No abstract