Luisa Schipilliti

Genuineness assessment of mandarin essential oils employing gas chromatography-combustion-isotope ratio MS (GC-C-IRMS)

Cold-pressed mandarin essential oils are products of great economic importance in many parts of the world and are used in perfumery, as well as in food products. Reconstituted mandarin oils are easy to find on the market; useful information on essential oil authenticity, quality, extraction technique, geographic origin and biogenesis can be attained through high-resolution GC of the volatile fraction, or enantioselective GC, using different chiral stationary phases. Stable isotope ratio analysis has gained considerable interest for the unveiling of citrus oil adulteration, detecting small differences in the isotopic carbon composition and providing plenty of information concerning the discrimination among products of different geographical origin and the adulteration of natural essential oils with synthetic or natural compounds. In the present research, the authenticity of several mandarin essential oils was assessed through the employment of GC hyphenated to isotope ratio MS, conventional GC flame ionization detector, enantioselective GC and HPLC. Commercial mandarin oils and industrial natural (declared as such) mandarin essential oils, characterized by different harvest periods and geographic origins, were subjected to analysis. The results attained were compared with those of genuine cold-pressed Italian mandarin oils, obtained during the 2008-2009 harvest season.

Multidimensional GC coupled to MS for the simultaneous determination of oxygenate compounds and BTEX in gasoline

In the present work, carried out in relation to the European and American Directives on the quality of petrol and diesel fuels, the simultaneous determination of the oxygenate compounds and BTEX in gasoline was achieved through the use of a multidimensional GC (MDGC)/MS system, employing a Deans switch-based transfer system, with an innovative configuration; the latter enabled multiple heart-cut transfers with no hint of retention time shift, a phenomenon that can occur in MDGC, providing the possibility to achieve more then 20 different heart-cuts for the compounds of interest. In this study, 20 selected compounds were quantitatively transferred with 12 heart-cuts, from a first to a secondary column, in order to resolve primary column co-elutions. Analyte quantification and identification was achieved through a fast-scanning quadrupole mass analyzer, operated in full scan mode, in order to evaluate also the interfering compounds transferred together with the compounds of interest. The multidimensional method developed was subjected to validation. All attained data were in excellent correlation with results obtained through the UNI-EN 12177:2000, ASTM D 5580-02 and ASTM D 4815-04 MDGC methods, for the determination of benzene, BTEX and oxygenate compounds in gasoline, respectively.

Headspace-solid phase microextraction coupled to gas chromatography–combustion-isotope ratio mass spectrometer and to enantioselective gas chromatography for strawberry flavoured food quality control

Authenticity assessment of flavoured strawberry foods was performed using headspace-solid phase microextraction (HS-SPME) coupled to gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). An authenticity range was achieved, investigating on the carbon isotope ratio of numerous selected aroma active volatile components (methyl butanoate, ethyl butanoate, hex-(2E)-enal, methyl hexanoate, buthyl butanoate, ethyl hexanoate, hexyl acetate, linalool, hexyl butanoate, octyl isovalerate, γ-decalactone and octyl hexanoate) of organic Italian fresh strawberries. To the authors knowledge, this is the first time that all these components were investigated simultaneously by GC-C-IRMS on the same sample. The results were compared, when applicable, with those obtained by analyzing the HS-SPME extracts of commercial flavoured food matrices. In addition, one Kenyan pineapple and one fresh Italian peach were analyzed to determine the δ(13)C(VPDB) of the volatile components common to strawberry. The δ(13)C(VPDB) values are allowed to differentiate between different biogenetic pathways (C(3) and CAM plants) and more interestingly between plants of the same CO(2) fixation group (C(3) plants). Additional analyses were performed on all the samples by means of Enantioselective Gas Chromatography (Es-GC), measuring the enantiomeric distribution of linalool and γ-decalactone. It was found that GC-C-IRMS and Es-GC measurements were in agreement to detect the presence of non-natural strawberry aromas in the food matrices studied.

Authentication of Bergamot Essential Oil by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometer (GC-C-IRMS)

Abstract The quality assessment of bergamot essential oils was established employing the gas chromatography-combustion- isotope ratio mass spectrometer (GC-C-IRMS) technique. An authenticity range was obtained investigating the carbon stable isotope ratio of genuine Italian bergamot essential oils (harvest period 2008–2009), in order to compare the GC-C-IRMS data of several industrial, commercial and foreign bergamot essential oil samples. Moreover, with the aim to test the efficiency and the sensibility of IRMS device, self-adulterated in laboratory bergamot oil samples were analyzed. The data were compared with those achieved by conventional enantioselective gas chromatography (Es-GC) and high resolution gas chromatography (GC-FID). Results of this work indicated that GC-C-IRMS was able not only to detect the presence of adulterants in the samples, but also to discriminate the bergamot oil samples according to their geographic provenance and the nature of the adulterants added.

Characterization of cold-pressed and processed bergamot oils by using GC-FID, GC-MS, GC-C-IRMS, enantio-GC, MDGC, HPLC and HPLC-MS-IT-TOF

Numerous samples of Italian cold-pressed bergamot oils, representative of the industrial production of the last three seasons (2008/09, 2009/10 and 2010/11), as well as several samples of bergapten-free, concentrated and recovered oils, have been extensively investigated in the present study. The samples were analyzed to determine the composition of the volatile fraction, the oxygen heterocyclic compounds, the enantiomeric distribution of twelve volatile components and the isotopic ratios of selected volatiles. Differences from previous studies emerged. The recent improvement in cultural practices is confirmed by the increase of linalool and linalyl acetate, indicative of better quality of the essential oils. The seasonal variation of the enantiomeric excess of α-terpineol, characteristic of cold-pressed bergamot oils, is confirmed. Some oxygen heterocyclic compounds are here quantitatively determined for the first time. The presence of herniarin is confirmed in genuine samples through high-pressure liquid-chromatography–mass spectrometry–ion trap–time of flight (HPLC-MS-IT-TOF). The isotopic ratios herein reported, for all the samples analyzed, represent a useful tool for the evaluation of genuineness of cold-pressed and processed bergamot oils.

Multidimensional enantio gas chromtography/mass spectrometry and gas chromatography-combustion-isotopic ratio mass spectrometry for the authenticity assessment of lime essential oils (C. aurantifolia Swingle and C. latifolia Tanaka)

This article focuses on the genuineness assessment of Lime oils (Citrus aurantifolia Swingle and C. latifolia Tanaka), by Multi Dimensional Gas Chromatography (MDGC) to determine the enantiomeric distribution of α-thujene, camphene, β-pinene, sabinene, α-phellandrene, β-phellandrene, limonene, linalool, terpinen-4-ol, α-terpineol and by gas chromatography-combustion isotope ratio mass spectrometry (GC-C-IRMS) to determine the isotopic ratios of α-pinene, β-pinene, limonene, α-terpineol, neral, geranial, β-caryophyllene, trans-α-bergamotene, germacrene B. To the authors knowledge this is the first attempt to assess the authenticity and differentiate Persian Lime from Key lime oils by GC-C-IRMS. The results of the two analytical approaches were compared. The simultaneous use of the two techniques provides more reliable capability to detect adulteration in Citrus essential oils. In fact, in some circumstance only one of the two techniques allows to discriminate adulterated or contaminated oils. In cases where only small anomalies are detected by the two techniques due to subtle adulterations, their synergic use allows to express judgments. The advantage of both techniques is the low number of components the analyst must evaluate, reducing the complexity of the data necessary to deal with. Moreover, the conventional analytical approach based on the evaluation of the whole volatile fraction can fail to reveal the quality of the oils, if the adulteration is extremely subtle.

Solid‐phase microextraction with fast GC combined with a high‐speed triple quadrupole mass spectrometer for targeted and untargeted food analysis

The present contribution is focused on the evaluation of a high-speed triple quadrupole mass spectrometer, carried out under moderately fast GC conditions (analysis time: 16.6 min). The mass spectrometric instrument can be operated under high-speed GC conditions, in both full-scan (maximum scan speed: 20 000 amu/s) and multiple reaction monitoring (MRM) modes (minimum dwell time: 0.01 s). Additionally, the mass spectrometric system can generate full scan and MRM information, simultaneously and rapidly. A headspace solid-phase microextraction with fast GC coupled to triple quadrupole MS approach was developed for the: (i) qualitative untargeted analysis of brewed tea volatiles, and (ii) MRM qualitative and quantitative analysis of targeted volatiles (also in brewed tea), namely 30 phytosanitary contaminants. The performance of the triple quadrupole instrument was satisfactory both for identification and quantification purposes. Furthermore, the method sensitivity was more than sufficient for the requirements of current legislation. Method validation, related to the MRM analysis, was performed considering: precision of quantification data (maximum coefficient of variation value: 12.0%) and quantification/qualification ion ratios (maximum coefficient of variation value: 14.4%), along with limits of detection (4 parts per trillion-5 parts per billion range) and quantification (14 parts per trillion-16 parts per billion range).

Determination of petitgrain oils landmark parameters by using gas chromatography–combustion–isotope ratio mass spectrometry and enantioselective multidimensional gas chromatography

Gas chromatography–combustion–isotope mass spectrometry was employed for the assessment of the Carbon isotope ratios of volatiles in Italian mandarin and lemon petitgrain oils. In addition, the composition of the whole oil and the enantiomeric distribution of selected chiral compounds were determined for all the samples by using gas chromatography and by multidimensional and conventional enantioselective gas chromatography. The composition of the oils was compared with previous studies. The enantiomeric distribution of lemon petitgrain oils is here reported for the first time. On the composition of mandarin petitgrain oil, the information available in literature, to date, is relative only to one sample from Egypt. Carbon isotope ratio of several terpene hydrocarbons and of their oxygenated derivatives contained in petitgrains was compared with the δ13CVPDB values of the same compounds present in the corresponding genuine Italian Citrus peel oil. The results prove that the isotopic values obtained for lemon and mandarin petitgrain oils are very close to those relative to the corresponding peel oils determined in previous studies.

Carbon isotope ratios of selected volatiles in Citrus sinensis and in orange-flavoured food

BACKGROUND Twenty genuine samples of industrially cold-pressed sweet orange essential oils, were analysed by gas chromatography-combustion-isotope ratio mass spectrometry to determine the values of the carbon isotope ratios (δ(13)C(VPDB)) of selected volatiles and assess the corresponding range of authenticity. Successively, four commercial orange-flavoured products were analysed under identical conditions to evaluate the authenticity of the orange flavour. The samples were extracted by solid-phase microextraction under optimised conditions. The evaluation was performed by using an internal standard procedure to neglect the contribution due to the original environment to the isotopic abundance of (13)C. The composition of the volatile fraction of the essential oils and of the flavoured products was determined by gas chromatography coupled to mass spectrometry with linear retention indices, and by gas chromatography with a flame ionisation detector. RESULTS The δ(13)C(VPDB) values of seven secondary metabolites determined here were successfully used to characterise genuine orange essential oil. These values were used to evaluate the quality of orange-flavoured products, revealing the presence of compounds of different origin, not compatible with the values of genuine orange secondary metabolites. CONCLUSIONS This study provides the range of authenticity of δ(13)C(VPDB) of seven different secondary metabolites in sweet orange genuine essential oil, useful for evaluating the genuineness of orange flavour. In accord with a previous study on different essential oils, the values determined here can be successfully applied for the evaluation of a large number of flavoured food stuffs and correlated with their origins.

Helichrysum italicum (Roth) G. Don fil. subsp. italicum oil analysis by gas chromatography – carbon isotope ratio mass spectrometry (GC-C-IRMS): a rapid method of genotype differentiation?

Abstract Helichrysum italicum (Roth) G. Don fil. subsp. italicum oils, coming from Sicily and Corsica and growing up, at equal geographical area, at the same edaphic and climatic conditions, were investigated by GC-MS, GC-FID and gas chromatography carbon isotope ratio mass spectrometry (GC-C-IRMS). GC-MS and GC-FID analyses on the oils terpene fraction have evidenced two different compositional finger prints (chemotypes). Investigating the carbon isotope ratio of the main and common terpene compounds, were also highlighted different plants’ genetic behaviors. The i-stds elaboration has permitted to investigate on the plants’ genetic changes, taking into account only the secondary biogenetic pathways, in which the terpenes formation occurs.