Giovanni Dugo

COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY-MASS SPECTROMETRY: A REVIEW

Although comprehensive two-dimensional gas chromatography (GC x 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 x 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 x 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 x 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 x GC are also described.

Protective Effects of Anthocyanins from Blackberry in a Rat Model of Acute Lung Inflammation

Anthocyanins are a group of naturally occuring phenolic compounds related to the coloring of plants, flowers and fruits. These pigments are important as quality indicators, as chemotaxonomic markers and for their antioxidant activities. Here, we have investigated the therapeutic efficacy of anthocyanins contained in blackberry extract (cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents) in an experimental model of lung inflammation induced by carrageenan in rats. Injection of carrageenan into the pleural cavity elicited an acute inflammatory response characterized by fluid accumulation which contained a large number of neutrophils as well as an infiltration of polymorphonuclear leukocytes in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NOx) and prostaglandin E2 (PGE2). All parameters of inflammation were attenuated in a dose-dependent manner by anthocyanins (10, 30 mg kg-1 30 min before carrageenan). Furthermore, carrageenan induced an upregulation of the adhesion molecule ICAM-1, nitrotyrosine and poly (ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining was lowered by anthocyanins treatment. Thus, the anthocyanins contained in the blackberry extract exert multiple protective effects in carrageenan-induced pleurisy.

Protective effects of cyanidin-3-O-glucoside from blackberry extract against peroxynitrite-induced endothelial dysfunction and vascular failure

Anthocyanins are a group of naturally occurring phenolic compounds as colorants in several plants, flowers and fruits. These pigments have a great importance as quality indicators, as chemotaxonomic markers and antioxidants. The content of blackberry (Rubus species) juice was investigated by HPLC/ESI/MS using narrow bore HPLC columns. Using this method we demonstrated that cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents in blackberry extract. Here we investigated antioxidant activity of the blackberry juice and cyanidin-3-O-glucoside on the endothelial dysfunction in cells and in vascular rings exposed to peroxynitrite. In human umbilical vein endothelial cells (HUVEC) in vitro, peroxynitrite caused a significant suppression of mitochondrial respiration (38 +/- 2.1% of control cells), as measured by the mitochondrial-dependent conversion of the dye MTT to formazan. Peroxynitrite caused DNA strand breakage (63 +/- 1.9% single strand vs 3 +/- 0.9% single strand in control cells), as measured by the alkaline unwinding assay, and caused an activation of PARS, as measured by the incorporation of radiolabeled NAD(+) to nuclear proteins. Blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3-O-glucoside (as chloride) (0.085 microM; 0.028 microM; 0.0085 microM) reduced the peroxynitrite-induced suppression of mitochondrial respiration, DNA damage and PARS activation in HUVECs. Vascular rings exposed to peroxynitrite exhibited reduced endothelium-dependent relaxant responses in response to acetylcholine as well as a vascular contractility dysfunction in response to norepinephrine. The development of this peroxynitrite-induced vascular dysfunction was ameliorated by the blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3-O-glucoside (as chloride) (0.085 microM;0.028 microM;0.0085 microM). In conclusion our findings clearly demonstrate that blackberry juice containing cyanidin-3-O-glucoside is a scavenger of peroxynitrite and that exert a protective effect against endothelial dysfunction and vascular failure induced by peroxynitrite.

LC-MS for the identification of oxygen heterocyclic compounds in citrus essential oils

The oxygen heterocyclic compounds (coumarins, psoralens and polymethoxylated flavones) present in the nonvolatile residue of the essential oils of Mandarin, Sweet Orange, Bitter Orange, Bergamot and Grapefruit were analysed with an HPLC/API/MS system equipped with an APcI probe in positive mode. The use of hyphenated techniques, such as LC/MS provides a great information about the content and nature of constituents of natural complex matrices, such as essential oils. In this work, MS spectra were recorded at different voltages, to obtain structural information in addition to molecular weight information. The different response of the compounds identified has been also evaluated. The method allowed the confirmation of the identification of the main components of the fraction, previously reported for the different oils. MS characteristics of coumarins, psoralens and polymethoxylated flavones with different substitution patterns were determined on the basis of the response obtained with the APcI interface. Interface parameters were optimised to obtain a contemporaneous response for all the three classes of components.

Detailed analysis and group-type separation of natural fats and oils using comprehensive two-dimensional gas chromatography

Comprehensive gas chromatography (GC x GC) is an adequate methodology for the separation and identification of very complex samples. It is based on the coupling of two capillary columns that each give a different but substantial contribution to the unprecedented resolving power of this technique. The 2D space chromatograms that derive from GC x GC analysis have great potential for identification. This is due to the fact that the contour plot positions, pinpointed by two retention time coordinates, give characteristic patterns for specific families of compounds that can be mathematically translated. This investigation concerned the application of this principle to fatty acid methyl esters that were grouped on an equal double bond number basis. The ester samples were derived from various lipids and all underwent bidimensional analysis on two sets of columns. Peak attribution was supported by mass spectra, linear retention indices and information reported in the literature.

Evaluation of a rapid-scanning quadrupole mass spectrometer in an apolar × ionic-liquid comprehensive two-dimensional gas chromatography system.

Comprehensive two-dimensional gas chromatography (GC×GC) is a powerful technique which can enable a great increase in GC peak capacities. However, since secondary-column separations are very rapid, detectors with a fast acquisition rate are mandatory. Such a requirement has certainly limited the use of the quadrupole mass spectrometer in the GC×GC field. The present research is focused on the evaluation of a novel rapid-scanning quadrupole mass spectrometry (qMS) detector, characterized by a 20,000 amu/s scan speed and a 50 Hz scan frequency, using a 290 amu mass range (40-330 m/z). The performance of the MS system was assessed by analyzing mixtures of 24 allergens, as well as a perfume sample, through GC×GC/qMS. The MS parameters evaluated at different acquisition rates (50, 33, and 25 Hz), as well as in the (simultaneous) scan/selected ion monitoring (SIM) mode, were the number of data points per peak, mass spectrum quality, peak skewing, and sensitivity. Two GC×GC/qMS methods, using the 50 Hz acquisition rate and the scan/SIM mode, were validated. Both methods provided similar results in terms of repeatability, accuracy, and linearity, while a great increase in sensitivity was observed (ca. a factor of 10) under scan/SIM conditions. The validated method proved to be suitable for the analysis of perfume allergens, according to the requirements of Directive 2003/15/EC.

Comprehensive normal-phase × reversed-phase liquid chromatography coupled to photodiode array and mass spectrometry detection for the analysis of free carotenoids and carotenoid esters from mandarin

In the present work, a novel strategy including the use of two different comprehensive HPLC methods has been employed to study the whole carotenoid composition of mandarin essential oil. Thus, two different fully orthogonal two-dimensional HPLC methods have been used. A silica microbore column was coupled to a C(18) monolithic column to study the mandarin saponified extract, while the coupling of a cyano microbore column to a C(18) monolithic column was employed to study the intact mandarin essential oil sample in order to characterize the native carotenoid esters composition. Detection was performed by connecting a photodiode array detection (DAD) system in parallel with a MS detection system operated with an atmospheric pressure chemical ionization (APCI) interface. Thus, the carotenoid identification was carried out by combining the information provided by the DAD and MS systems and the peaks relative position in the two-dimensional chromatograms.

Evaluation of use of a dicationic liquid stationary phase in the fast and conventional gas chromatographic analysis of health-hazardous C18 cis/trans fatty acids.

The present research is focused on the evaluation of one 0.10 mm i.d. and two 0.25 mm i.d., ionic liquid (IL) stationary phase [1,9-di(3-vinyl-imidazolium) nonane bis(trifluoromethyl) sulfonyl imidate] columns, with lengths of 12 (the microbore capillary), 30 and 100 m, in the GC analysis of cis/trans fatty acid methyl esters (FAMEs). The selectivity of the IL columns toward a series of standard C(18:1), C(18:2), and C(18:3) geometric isomers (a group of 22 compounds was subjected to GC analysis) was compared to the performance of a widely used column in the cis/trans FAMEs analysis field, viz., a 100 m x 0.25 mm i.d. capillary with a 0.20 microm stationary phase film of bis-cyanopropyl polysiloxane (SP-2560). The selectivity provided by the IL phase was superior if compared to that of the other well-established capillary. An optimized IL method, using the longer column, was subjected to validation: retention time and peak area intraday precision (n = 5) were good, with RSD values lower than 0.07% and 6.6%, respectively; LODs (considering a S/N of 3) for C(18:1Delta)(9tr) and C(18:2Delta)(9tr,12tr) were 0.15 (7.3 ppm) and 0.18 ng (9.1 ppm) on-column, respectively, while LOQs (considering a S/N of 10) were 0.49 (24.3 ppm) and 0.60 ng (30.2 ppm), respectively; the method was found to be linear, for both trans FAMEs, in the 10-2000 ppm range. For the evaluation of accuracy, a hydrogenated margarine, spiked with known amounts of C(18:3Delta)(9c,12c,15c), was subjected to analysis using C(13:0) as an internal standard.

Citrus: The Genus Citrus

Citrus: The Genus Citrus offers comprehensive coverage on all aspects of the botany, cultivation, processing industry, chemistry and uses of Citrus and its oils. It describes the different citrus species; their environmental, geographical, and historical context; and their chemical composition and properties in detail. Following a chapter on citrus juice technology, the international panel of contributors describe the stages of preparation and processing methods of the juice, from cold extraction and distillation to the use of supercritical fluids, and the chemical reactions involved. The authors also discuss by-products, quality control, world markets, and regulations in the industry, and how analytical methods, such as mass spectrometry and HPLC, are used to characterize the Citrus essential oils. Citrus: The Genus Citrus explores the current and future applications of Citrus oils, which include flavorings for alcohol, soft drinks, food, as well as fragrances for cosmetics and beauty products. Authors also discuss the therapeutic properties of these oils in traditional medicine and modern pharmaceuticals. Anyone involved in food sciences, pharmaceutical sciences, cosmetics, and plant sciences will no doubt find this volume to be of great value and interest.

Ochratoxin A occurrence in experimental wines in relationship with different pesticide treatments on grapes

Abstract A reversed-phase HPLC method was utilized for Ocrhratoxin A (OTA) determination in 23 white and red wine samples produced in the year 2000. All were come from some vineyards, treated with different pesticides, located in three Italian regions. Analytical methods included commercial immunoaffinity columns and a HPLC system equipped with a RF detector. The sensitivity of the analytical method was 0.01 ng ml −1 . Values of OTA found in wine samples show that OTA is more frequently detected in red than in white wines. In fact, all red wine samples were contaminated. The OTA levels reported in this work are comparable with those reported for mycotoxin in red wine. Moreover, the different contents of Ochratoxin A in the wines can be considered an efficiency index of pesticides used.