T. Cecchi

Volatile profiles of Italian monovarietal extra virgin olive oils via HS-SPME-GC-MS: newly identified compounds, flavors molecular markers, and terpenic profile.

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from Italy (Marche region), renowned since ancient times. Headspace solid-phase micro-extraction (HS-SPME) was applied for the very first time to the sampling of volatile compounds of eleven typical Italian monocultivar EVOOs. Forty-eight compounds were characterised by GC-MS, some of them were only occasionally found in other EVOOs and some other were never detected before in any EVOO. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles. The main volatile compounds detected in the EVOOs were the C6 compounds derived from polyunsaturated fatty acids, through the lipoxygenase pathway, in different proportion according to the specific cultivar. The results suggest that genetic factors strongly influence volatile formation and terpene hydrocarbons are claimed to be suitable markers of the geographic origin and genotype of the EVOO. Correlations among sensory attributes evaluated by a panel test and the presence of specific volatile compounds were highlighted for the very first time. The significance of the presence of some newly identified volatile compounds was discussed.

Ion interaction chromatography of neutral molecules

SummaryThe chromatographic behavior of neutral molecules in ion-interaction chromatography (IIC) is investigated theoretically. The physical and chemical modification of the stationary phase in the presence of ion interaction Reagent (IIR) in the eluent, and adsorption competition between test analytes and IIR for inner layer sites are shown theoretically to change the partition coefficient of neutral molecules.The most reliable, literature experimental results, concerming retention behaviour of neutral molecules in IIC, were used to test the new theory. The wide variability among them was elucidated on the basis of the exhaustive retention model developed. Retention equations were compared to those which can be obtained, if the change of the analyte is zero, from the most important retention model in IIC.

The dipole approach in ion-interaction chromatography of zwitterions

SummaryThe chromatographic behavior of zwitterions in Ion-interaction chromatography (IIC) is, investigated theoretically for the first time. The modification of the stationary phase in the presence of Ion-interaction reagent (IIR), and adsorption competition between test analytes and IIR for inner layer sites are shown theoretically to change the partition coefficient for zwitterions.Experimental results from the literature concerning retention behavior of zwitterions in IIC, were used to test the new thermodynamic theory. Very reasonable estimates of (i) ΔGo values for the IIR adsorption onto the stationary phase (II) total ligand concentration, and (iii) dipolar moments validate the present thermodynamic model for the IIC of zwitterionic analytes.Retention equations are compared to those which can be obtained, if the net charge of the analyte is zero, from the most important retention models in IIC. None of them is able to explain, even in a qualitative way, the retention behavior of zwitterions in IIC whereas, the present model is quantitatively able to do this.

Extended thermodynamic approach to ion interaction chromatography: effect of the electrical charge of the solute ion

Abstract The chromatographic behavior of multiply charged analytes in ion interaction chromatography (IIC) was theoretically investigated. Practical equations that describe the relationship between the retention factor and the concentration of the ion interaction reagent (IIR) were developed. They can be used to model analyte retention as a function of both the mobile and stationary phase concentrations of the IIR. A comparison between the retention behaviour of singly and doubly charged analytes is given.

Monovarietal Extra Virgin Olive Oils from the Marche Region, Italy: Analytical and Sensory Characterization

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from the Marche region (Italy), renowned since ancient times. The chemical composition of all the most typical monovarietal oils collected in four crop seasons, was studied in relation to the year of harvesting (from 2004–2007) and the genotype. In order to obtain a complete description of oil samples, free acidity, peroxide value, fatty acid composition, ultraviolet indices, carotenoids, chlorophylls, and phenols were determined. The main characteristics of these oils are large total phenol content, low acidity and peroxide values, low oxidative susceptibilities. All the chemical parameters fell within the limits established for the maximum olive oil category. Sensory evaluation showed that the total score of all the monovarietal extra virgin olive oils was always much higher than the 6.5 limit established for the ‘extra-virgin’ category. The overall quality indices support claims of excellence for monovarietal EVOOs from this geographical area. Results from the present study are of key importance for the specific Production Standards a document that contains regulations for supervising the entire olive oil production cycle and a prerequisite for both the European Protected Denomination of Origin (PDO) and Quality granted by the Marche region (QM) labels.

Ion-interaction chromatography of zwitterions. The fractional charge approach to model the influence of the mobile phase concentration of the ion-interaction reagent

The chromatographic behavior of zwitterions in ion-interaction chromatography (IIC) was investigated theoretically, on the basis of the following picture of the retention mechanism. The zwitterionic analyte is considered to interact with the charged stationary phase via an effective fractional charge, opposite to the surface one. Adsorption competitions between analytes and the ion interaction reagent (H) concur to explain the retention factor of zwitterions. The present model is quantitatively able to explain the retention behavior of zwitterions in IIC and also to account for the influence of the zwitterion ionization degree, according to the mobile phase pH, on the course of retention as a function of the H concentration. The approach we used is simple and epistemologically interesting because the retention equation for zwitterions may also be obtained from the general retention equation of our extended thermodynamic approach to IIC. Estimated magnitudes of the effective charges are very reasonable and show the same trend as that of the molecular dipole moments, as expected; the total ligand concentration compares well with the bonded phase coverage of the two columns used. For the homologous series from 4-aminobutyric-, to 8-aminocaprylic acid, the estimated effective charge always increases with increasing chain length and this results in parallel growth of the analyte retention increase upon H addition, so that the retention increase for the highest member of the series compares with that of a positively charged analyte. The estimated dipole for this analyte compares excellently to the estimate obtained via a quantum mechanics calculation. The influence of the mobile phase pH on retention was taken into account for the very first time. The good predictive abilities of the retention equations, and the reliability of the estimated constants that make sense physically confirm that retention modeling is able, at the thermodynamic level, to disclose the complexity of the IIC system.

Microbiological characterisation and volatiles profile of model, ex-novo, and traditional Italian white wheat sourdoughs

The interplay of sourdough microbiology and generated volatile compounds that define its sensory characteristics was studied. In order to detail the flavour generating potential of microorganisms, eight single-strain dough fermentations were studied, four of them never investigated before. Moreover, for the first time, both ex-novo and traditional wheat sourdoughs were investigated and compared to chemically acidified dough. HS-SPME-GC-MS was used to sample and analyse volatile compounds, some of which have never been detected before in sourdoughs. Alcohols, esters, carbonyl compounds, and acids mainly characterised the volatile profiles. Different sourdough microbiota resulted in different volatile profiles. PCA indicated that samples could be clustered according to their specific microbiota. Production of aroma compounds was strain-specific, confirming previous findings. This study can contribute to the management of desirable features and differentiate specialty products, as well as selecting new, suitable, sourdoughs after microbial screening.

Application of Ion Pairing Chromatography to the Analysis of Inorganic Analytes: Review

Abstract The separation challenges that keep arising from the constantly evolving practical applications encountered in ion‐pair chromatography (IPC) of inorganic analytes and inorganic elements containing compounds are reviewed. Emphasis is placed on species that are most important in the biochemical, biomedical areas or that are of concern in the environmental field. Examples will be given of the analysis and speciation of a wide variety of compounds in different matrixes. They assess the practical potential of this mature technique whose results are usually in agreement with those obtained via different analytical strategies. Eclectic hyphenations to achieve specific goals are also described.

Theoretical Models of Ion Pair Chromatography: A Close Up of Recent Literature Production

The use of ionic additives to dramatically extend the range of solute polarity amenable to RP-HPLC began to be exploited in the 1970s. Ion pair chromatography has readily become an intriguing separation strategy: it makes use of ionic Ion Pair Reagents to increase retention of oppositely charged analytes, under RP-HPLC conditions. It is also well recognized that these additives have a significant influence on the peak shape of ionogenic analytes and on the figures of merit of their chromatographic separations. As evidenced by the studies described in this review, retention modeling may offer much potential to help chromatographers perform educated guesses and shorten the optimization process of separations. Although the last years have seen many application of IPC in routine analyses, there is a minimal amount of published work concerning retention modeling in IPC. The purpose of the current review is to bridge the past with the future, with regard to the theoretical facets of this technique, and to provide a critical and comparative survey of the latest theoretical advances in IPC.

Extended thermodynamic approach to ion-interaction chromatography for high surface potential: use of potential approximation for simplified retention equations

SummaryThe chromatographic behaviour of charged analytes in ion interaction chromatography (IIC) has been investigated theoretically. A potential approximation for high surface potential was used to obtain simplified retention equations that are able to model analyte retention as a function of both the mobile and stationary phase concentrations of the ion-interaction reagent (IIR). The main advantage of using this potential approximation is that it allows calculation of the surface potential, without needing detailed information on physical and chemical properties of the mobile phase.Retention equations of previous thermodynamic retention models can be viewed as limiting cases of the present theory. One of the most reliable data sets conceming the retention behaviour of charged substances in IIC, obtained at high surface potential, was used to test the new retention equations.