Rosaria Costa

Electronic nose and GC-MS analysis of volatile compounds in Tuber magnatum Pico: evaluation of different storage conditions.

The characteristic aromatic composition of white truffles (Tuber magnatum Pico) determines its culinary and commercial value. However modifications of truffle organoleptic proprieties occur during preservation. A study of headspace of white truffles by using Electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS) and sensory analyses was performed. Truffles were stored at different conditions for 7 days: +4 and +8°C wrapped in blotting paper or covered by rice or none of the above. Headspace E-nose measurements and sensory analyses were performed each day. Statistical multivariate analysis of the data showed the capability of E-nose to predict sensorial analysis scores and to monitor aroma profile changes during storage. Truffles volatile molecules were also extracted by headspace solid phase microextraction technique and separated and identified by GC-MS. Partial Components Analysis of data was performed. E-nose and GC-MS results were in agreement and showed that truffle storage in paper at +8°C seemed to be the best storage condition.

Newly Introduced Sample Preparation Techniques: Towards Miniaturization

Sampling and sample preparation are of crucial importance in an analytical procedure, representing quite often a source of errors. The technique chosen for the isolation of analytes greatly affects the success of a chemical determination. On the other hand, growing concerns about environmental and human safety, along with the introduction of international regulations for quality control, have moved the interest of scientists towards specific needs. Newly introduced sample preparation techniques are challenged to meet new criteria: (i) miniaturization, (ii) higher sensitivity and selectivity, and (iii) automation. In this survey, the most recent techniques introduced in the field of sample preparation will be described and discussed, along with many examples of applications.

Acquisition of deeper knowledge on the human plasma fatty acid profile exploiting comprehensive 2‐D GC

The present research is focused on the use of comprehensive 2-D GC (GC x GC) for the elucidation of the human plasma fatty acid (FA) profile. The enhanced sensitivity, increased separation power and the formation of group-type patterns provided by GC x GC enabled the identification and quantification of a high number of both well known and unexpected FAs, for a total of 65 components. Peak assignment was, in most cases, supported by using pure standard compounds. The results attained demonstrated the usefulness of the multidimensional GC method in this fundamental field of research.

Multiple headspace-solid-phase microextraction: an application to quantification of mushroom volatiles.

Multiple headspace-solid phase microextraction (MHS-SPME) followed by gas chromatography/mass spectrometry (GC-MS) and flame ionization detection (GC-FID) was applied to the identification and quantification of volatiles released by the mushroom Agaricus bisporus, also known as champignon. MHS-SPME allows to perform quantitative analysis of volatiles from solid matrices, free of matrix interferences. Samples analyzed were fresh mushrooms (chopped and homogenized) and mushroom-containing food dressings. 1-Octen-3-ol, 3-octanol, 3-octanone, 1-octen-3-one and benzaldehyde were common constituents of the samples analyzed. Method performance has been tested through the evaluation of limit of detection (LoD, range 0.033-0.078 ng), limit of quantification (LoQ, range 0.111-0.259 ng) and analyte recovery (92.3-108.5%). The results obtained showed quantitative differences among the samples, which can be attributed to critical factors, such as the degree of cell damage upon sample preparation, that are here discussed. Considerations on the mushrooms biochemistry and on the basic principles of MHS analysis are also presented.

Application of a multidimensional gas chromatography system with simultaneous mass spectrometric and flame ionization detection to the analysis of sandalwood oil

The production and trade of Indian sandalwood oil is strictly regulated, due to the impoverishment of the plantations; for such a reason, Australian sandalwood oil has been evaluated as a possible substitute of the Indian type. International directives report, for both the genuine essential oils, specific ranges for the sesquiterpene alcohols (santalols). In the present investigation, a multidimensional gas chromatographic system (MDGC), equipped with simultaneous flame ionization and mass spectrometric detection (FID/MS), has been successfully applied to the analysis of a series of sandalwood oils of different origin. A detailed description of the system utilized is reported. Three santalol isomers, (Z)-α-trans-bergamotol, (E,E)-farnesol, (Z)-nuciferol, epi-α-bisabolol and (Z)-lanceol have been quantified. LoD (MS) and LoQ (FID) values were determined for (E,E)-farnesol, used as representative of the oxygenated sesquiterpenic group, showing levels equal to 0.002% and 0.003%, respectively. A great advantage of the instrumental configuration herein discussed, is represented by the fact that identification and quantitation of target analytes are carried out in one step, without the need to perform two separate analyses.

Characterization of Oils from the Fruits, Leaves and Flowers of the Bitter Orange Tree

Abstract The bitter orange tree is used to obtain different products: essential oil cold pressed from the peel of the fruit, the neroli distilled from the flowers, the petitgrain distilled from the leaves and twigs, and different other products obtained by solvent extraction or by hydrodistillation. All these products are much appreciated for their odor properties. Their analytical characterization is important for the Identification of quality parameters, and considering their commercial value, it is important to determine their composition. This study is meant to determine differences between Italian and Egyptian cold-pressed, neroli and petitgrain oils, and gives useful information on the composition of the essential oil obtained from the whole crushed fruits. The composition of all the samples was studied by different analytical techniques to determine the volatile fraction, the enantiomeric distribution of some volatiles (by GC, GC/MS and esGC, respectively) and the oxygen heterocyclic fraction by RP-HPLC.

Essential oil composition of Citrus medica L. Cv. Diamante (Diamante citron) determined after using different extraction methods

In this paper, we report the qualitative and quantitative composition of the volatile and the oxygenated heterocyclic fraction of citron (Citrus medica L. cv. Diamante (Diamante citron)). The fruits selected for the extraction were of three types: green citron of little size, green citron of big size, and yellow citron after 1 month from the harvest. The essential oils were extracted using three different methods. The nine samples of oil thus obtained were analyzed by high resolution GC (HRGC)-flame ionization detection (FID), HRGC-MS, and RP-HPLC. They differ only in the quantitative composition, while the qualitative profile was the same. The volatile fraction of every sample of oil is characterized by a high content of limonene, gamma-terpinene, and monoterpene aldehydes and a lower content of alpha- and beta-pinene and myrcene, sesquiterpenes, and aliphatic aldehydes. Enantioselective (Es)-GC analysis of the extracts allowed the determination of the enantiomeric distribution of five terpenoid compounds; a prevalence of four dextrorotatory isomers was observed. Oxypeucedanin was the main component of the oxygenated heterocyclic fraction in the extracts of green fruits, while citropten was the major oxygenated compound in the oil obtained from yellow citron.

Offline LC‐GC×GC in combination with rapid‐scanning quadrupole mass spectrometry

The present research is focused on the offline combination of normal-phase LC to double-oven GC x GC-quadrupole MS. Initially, a diesel sample was subjected to automated LC x GC in order to define the elution windows of four fractions, viz., saturated hydrocarbons, monocyclic aromatics, dicyclic aromatics, tri- + tetracyclic aromatics; each fraction was collected exploiting the LC system in a further analysis and subjected to large-volume-injection-GC x GC analysis using an apolar-polar column combination. The GC x GC operational conditions were tuned in relation to the specific separation requirements of each heart-cut. The main benefits of what can be defined as offline LC-GC x GC were: (i) the high first-dimension LC selectivity; (ii) the injection of high sample amounts in the GC x GC system, enabling the detection and quantification of a series of low-amount diesel constituents; (iii) improved GC x GC operational conditions for each heart-cut with respect to direct GC x GC.

Determination of the triacylglycerol fraction in fish oil by comprehensive liquid chromatography techniques with the support of gas chromatography and mass spectrometry data

AbstractFish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge number has never been reported for a menhaden oil sample.The main disadvantage of such an approach over the stop-flow one was the longer analysis time, mainly attributable to solvent exchange between the two dimensions. Graphical AbstractTop: stop-flow Ag+-LC × RP-LC-APCI-MS plot of the TAGs in menhaden oil. Bottom: modulated detector response. Left: 2D analysis of a selected fraction

Sample preparation techniques coupled to advanced chromatographic methods for marine organisms investigation

OBJECTIVE of this work was to develop suitable extraction methodologies for the isolation of lipids from fish, mussels and clams from the Mediterranean sea, and their successive analysis by means of advanced chromatographic instrumentation. More specifically, three different sample preparation methodologies were adopted: Folchs, Bligh & Dyers and maceration. The lipidic extracts, after application of two different methylation procedures, were subjected to monodimensional and comprehensive two-dimensional GC analyses, in order to compare the fingerprints of samples derived from different extraction and transesterification methodologies. Triacylglycerols (TAGs) were analyzed by an off-line combination of silver-ion liquid chromatography with non-aqueous reversed phase liquid chromatography. In both LC and GC analyses, mass spectrometric detectors were used, which greatly supported the identification procedure. In particular, with respect to HPLC, mass spectrometry with atmospheric pressure chemical ionization in positive mode was applied.