PubMed Health⌕ Search

Biomedical subjects

Carlo Bicchi

Publications and source records attributed to Carlo Bicchi.

16 recordsLinked to original sources
PubMed2006

Analytical discrimination of poisonous and nonpoisonous chemotypes of giant fennel (Ferula communis L.) through their biologically active and volatile fractions.

Giant fennel (Ferula communis L.) from Sardinia is characterized by two chemotypes with different biological activities. One chemotype is poisonous, due to prenylcoumarins, and responsible for ferulosis, which mainly affects sheep and goats, cattle, and horses; the other chemotype is nonpoisonous and contains daucane esters. The two chemotypes cannot be distinguished botanically. High-performance liquid chromatography-diode array-ultraviolet detection-mass spectrometry (HPLC-DAD-UV-MS) analysis of the composition of the fractions containing the biologically active metabolites and of the volatile fractions, by gas chromatography-mass spectrometry (GC-MS), of both essential oil and headspace sampled by headspace solid-phase microextraction (HS-SPME) are here shown to be effective in discriminating the poisonous and nonpoisonous chemotypes. HS-SPME with CAR/PDMS/DVB in combination with GC-MS has also been found to be a successful, fully automated one-step method for rapid and unequivocal discrimination of the two chemotypes, using aristolene and allohedycaryol as markers of the poisonous and nonpoisonous chemotypes, respectively.

Chromatography, High Pressure Liquid↗
PubMed2006

Identification, quantitation and method validation for the analysis of suspected allergens in fragrances by comprehensive two-dimensional gas chromatography coupled with quadrupole mass spectrometry and with flame ionization detection.

The first part of this study first aims at validating a method to identify suspected allergens limited by EU regulations in fragrances by comprehensive two-dimensional gas chromatography (GC x GC) coupled with rapid scanning quadrupole MS (GC x GC-qMS). The effectiveness of the quadrupole MS operating at different scanning speed (1000 and 11,111 amu/s) was evaluated in identifying (full scan mode acquisition--TIC) and in quantifying (single ion monitoring--SIM) the target analytes in complex mixtures. In full scan acquisition mode the mass range was reduced to 40-240 amu to increase the scan acquisition rate while in SIM mode the influence of different dwell-times (40, 10 and 5 ms) was tested. The number of scans for each single modulated chromatographic GC x GC peak and the total number of scans for the 2D peak, together with half height peak width (referred to apex) of each allergen in the standard mixture in both TIC and SIM modes were determined. Moreover, the match quality of the spectra obtained by GC/MS at 1000 and 11,111 amu/s and by GC x GC-MS at 11,111 amu/s were compared and the occurrence of spectral skewing verified. In the second part of this work quantitative methods by GC x GC-SIM/qMS and GC x GC-FID were validated on the basis of Eurachem/CITAC protocols through which the following performance parameters were determined: confirmation of identity, selectivity and specificity, limit of detection (LOD), limit of quantitation (LOQ), linearity (working and linear range), precision and accuracy and uncertainty. Suspected allergens were spiked in a concentration range between 2 and 25 ppm (microg/mL) on a Test fragrance taken as a reference, while 1,4 dibromo-benzene and 4,4'-dibromodiphenyl were used as internal standards.

Allergens↗
PubMed2006

Comprehensive two-dimensional gas chromatography in the analysis of volatile samples of natural origin: a multidisciplinary approach to evaluate the influence of second dimension column coated with mixed stationary phases on system orthogonality.

The study evaluates the influence of selectivity tuning of the stationary phase of the second dimension on the orthogonality of a comprehensive two-dimensional gas chromatography (GC x GC) system. Two different sets of columns, providing independent and semi-independent separation mechanisms were used. The first consisted of a first dimension separating analytes on a volatility basis (i.e. a non-polar polydimethylsiloxane (OV1) column) combined with a second dimension separating by polarity, using columns coated with 100% polyethylene glycol (CW20M), CW20M/OV1 mixtures in ratios of 25-75%, and polydimethylsiloxane, 7% phenyl, 7% cyanopropyl (OV1701). The second set consisted of a first dimension separating analytes on a polarity basis (100% CW20M column) combined with a second dimension separating by volatility, consisting of columns coated with 100% OV1, OV1/CW20M mixtures in ratios of 25-75%, and 100% OV1701. Medium-complexity mixtures of natural origin (i.e. peppermint essential oil and a standard mixture of suspected allergens) consisting of components in a relatively limited range of molecular weights (MW) and volatilities, but belonging to different classes of compounds in a wide range of polarity (mono- and sesquiterpenoids, hydrocarbons and oxygenated compounds) were analysed with the above sets of columns. Different approaches were used to evaluate peak spreading on the GC x GC separation plane and degree of orthogonality of the column sets, namely: (1) a Factor Analysis (FA) approach, estimating the correlation coefficients and spreading angles of the sample components in the two-dimensional chromatographic plane; (2) an Informational Theory (IT) approach, based on determining a group of parameters including: informational entropy, % synentropy and similarity (H); and (3) an approach based on estimating the amount of separation space used, i.e. a practical parameter that directly refers to the experimental separation plane of the GC x GC chromatogram. Results showed that peak spreading in the chromatographic plane, when CW20M and OV1 are combined in different ratios, can be predicted from retention mechanisms, and that the degree of orthogonality measured with different approaches, is consistent with the divergent nature, in terms of polarity of the stationary phases combined in the GC x GC system.

Allergens↗
PubMed2006

Headspace-solid-phase microextraction in the analysis of the volatile fraction of aromatic and medicinal plants.

Headspace (HS)-solid-phase microextraction (SPME) has assumed an ever increasing importance as a technique for HS sampling to study the composition of the HS of medicinal and aromatic plants. HS-SPME has mainly been applied for (a) studying the composition of the volatile fraction, including in addition to or as an alternative to other sampling techniques; (b) monitoring the biological phenomena involved with the volatile fraction of a plant; (c) discriminating between species, subspecies, varieties, cultivars, or chemotypes; and (d) quality control of plant samples. A review of 108 articles published during 2000-2005 is presented covering the use of HS-SPME in the field of aromatic and medicinal plants, selection of the most effective fiber and sampling conditions, comparison of HS-SPME and other volatile fraction sample preparation techniques, and the advantages and limits of HS-SPME when applied to medicinal and aromatic plants.

Chromatography, Liquid↗
PubMed2005

Focused microwave-assisted extraction combined with solid-phase microextraction and gas chromatography-mass spectrometry for the selective analysis of cocaine from coca leaves.

An effective combination of focused microwave-assisted extraction (FMAE) with solid-phase microextraction (SPME) prior to gas chromatography (GC) is described for the selective extraction and quantitative analysis of cocaine from coca leaves (Erythroxylum coca). This approach required switching from an organic extraction solvent to an aqueous medium more compatible with SPME liquid sampling. SPME was performed in the direct immersion mode with a universal 100 microm polydimethylsiloxane (PDMS) coated fibre. Parameters influencing this extraction step, such as solution pH, sampling time and temperature are discussed. Furthermore, the overall extraction process takes into account the stability of cocaine in alkaline aqueous solutions at different temperatures. Cocaine degradation rate was determined by capillary electrophoresis using the short end injection procedure. In the selected extraction conditions, less than 5% of cocaine was degraded after 60 min. From a qualitative point of view, a significant gain in selectivity was obtained with the incorporation of SPME in the extraction procedure. As a consequence of SPME clean-up, shorter columns could be used and analysis time was reduced to 6 min compared to 35 min with conventional GC. Quantitative results led to a cocaine content of 0.70 +/- 0.04% in dry leaves (RSD <5%) which agreed with previous investigations.

Chemical Fractionation↗
PubMed2005

Dual-phase twisters: a new approach to headspace sorptive extraction and stir bar sorptive extraction.

The fields of applicability of headspace sorptive extraction (HSSE) and stir bar sorptive extraction (SBSE) using polydimethylsiloxane (PDMS) as sorbent have been intensively discussed and widely described. One of the limits of sorptive extraction is that PDMS (i.e. an apolar phase) is the only polymer currently in use making it difficult to recover polar analytes from complex or multi-ingredient matrices and those with very volatile components (C1-C4 analytes). Dual-phase twisters are here introduced as new tools for HSSE and SBSE to overcome the above limits. Dual-phase twisters combine the concentration capabilities of two or more sampling materials operating in different ways (in this case sorption and adsorption). The new twisters consist of a short PDMS tube the ends of which are closed with two magnetic stoppers, thus creating an inner cavity that can be packed with different types of adsorbents like activated carbons. The concentration capability of dual-phase twisters was evaluated by using them for the HSSE and SBSE sampling of a number of matrices in the vegetable, food and environmental fields. The contributions made by different carbons to recovery, repeatability and intermediate precision were also investigated.

Chromatography, Gas↗
PubMed2005

Impact of phase ratio, polydimethylsiloxane volume and size, and sampling temperature and time on headspace sorptive extraction recovery of some volatile compounds in the essential oil field.

This study evaluates concentration capability of headspace sorptive extraction (HSSE) and the influence of sampling conditions on HSSE recovery of an analyte. A standard mixture in water of six high-to-medium volatility analytes (isobutyl methyl ketone, 3-hexanol, isoamyl acetate, 1,8-cineole, linalool and carvone) was used to sample the headspace by HSSE with stir bars coated with different polydimethylsiloxane (PDMS) volumes (20, 40, 55 and 110 microL, respectively), headspace vial volumes (8, 21.2, 40, 250 and 1000 mL), sampling temperatures (25, 50 and 75 degrees C) and sampling times (30, 60 and 120 min, and 4, 8 and 16 h). The concentration factors (CFs) of HSSE versus static headspace (S-HS) were also determined. Analytes sampled by the PDMS stir bars were recovered by thermal desorption (TDS) and analysed by capillary GC-MS. This study demonstrates how analyte recovery depends on its physico-chemical characteristics and affinity for PDMS (octanol-water partition coefficients), sampling temperatures (50 degrees C) and times (60 min), the volumes of headspace (40 mL) and of PDMS (in particular, for high volatility analytes). HSSE is also shown to be very effective for trace analysis. The HSSE CFs calculated versus S-HS with a 1000 mL headspace volumes at 25 degrees C during 4 h sampling ranged between 10(3) and 10(4) times for all analytes investigated while the limits of quantitation determined under the same conditions were in the nmol/L range.

Dimethylpolysiloxanes↗
PubMed2004

Automated headspace solid-phase dynamic extraction to analyse the volatile fraction of food matrices.

High concentration capacity headspace techniques (headspace solid-phase microextraction (HS-SPME) and headspace sorptive extraction (HSSE)) are a bridge between static and dynamic headspace, since they give high concentration factors as does dynamic headspace (D-HS), and are as easy to apply and as reproducible as static headspace (S-HS). In 2000, Chromtech (Idstein, Germany) introduced an inside-needle technique for vapour and liquid sampling, solid-phase dynamic extraction (SPDE), also known as "the magic needle". In SPDE, analytes are concentrated on a 50 microm film of polydimethylsiloxane (PDMS) and activated carbon (10%) coated onto the inside wall of the stainless steel needle (5 cm) of a 2.5 ml gas tight syringe. When SPDE is used for headspace sampling (HS-SPDE), a fixed volume of the headspace of the sample under investigation is sucked up an appropriate number of times with the gas tight syringe and an analyte amount suitable for a reliable GC or GC-MS analysis accumulates in the polymer coating the needle wall. This article describes the preliminary results of both a study on the optimisation of sampling parameters conditioning HS-SPDE recovery, through the analysis of a standard mixture of highly volatile compounds (beta-pinene, isoamyl acetate and linalool) and of the HS-SPDE-GC-MS analyses of aromatic plants and food matrices. This study shows that HS-SPDE is a successful technique for HS-sampling with high concentration capability, good repeatability and intermediate precision, also when it is compared to HS-SPME.

Food Analysis↗
PubMed2004

Direct resistively heated column gas chromatography (Ultrafast module-GC) for high-speed analysis of essential oils of differing complexities.

This study applies Ultrafast module-GC (UFM-GC) with direct resistively heated columns to routine analysis of a group of essential oils of differing complexities (chamomile, peppermint, rosemary and sage). Essential oils were analysed by conventional GC with conventional inner diameter (i.d.) columns (0.25 mm) of different lengths (5 and 25 m long) and by Fast GC and Ultrafast module-GC with narrow bore columns (0.1 mm i.d., 5 m long). Column performance were evaluated and compared through their Grob test, separation number and peak capacity. Ultrafast module-GC was successful in the qualitative and quantitative analysis of essential oils of different compositions with analysis times between 40 s and 2 min versus 20-60 min required by conventional GC. Critical pairs or groups of components were separated by carefully tuning selectivity of the stationary phase to compensate for loss of efficiency due to the use of short columns and high temperature rates. The Ultrafast module-GC results of peppermint e.o. analyses were also validated and compared to those obtained by conventional GC; by measuring precision over time (i.e. repeatability and intermediate precision) and accuracy. Ultrafast module-GC showed a good separation reproducibility affording reliable component identification through the relative retention times and quantitative determination through normalised peak areas. Accuracy data also showed that Ultrafast module-GC and conventional GC normalised areas and areas percentage were perfectly comparable.

Chromatography, Gas↗
PubMed2004

New chiral selectors: design and synthesis of 6-TBDMS-2,3-methyl beta-cyclodextrin 2-2' thioureido dimer and 6-TBDMS-2,3-methyl (or 2-methyl-3-acetyl) beta-cyclodextrin bearing an (R) Mosher acid moiety.

Cyclodextrin (CD) derivatives are important selectors for analytical chiral recognition. Their enantioselectivities and chemical properties depend on ring size and on nature, number and location of substituents. This paper describes the synthesis of 6-O-TBDMS-2,3-O-methyl beta-cyclodextrins bearing in position 2 either a single (R)-Mosher acid moiety or a second CD unit, in view of their possible application as chiral selectors. Most synthetic steps were successfully carried out under high-intensity ultrasound using a new sonochemical reactor developed in the authors' laboratory. 6-O-TBDMS-2-O-methyl-3-[(S)-2-methylbutyl]-beta-CD was also synthesized and tested with gas chromatography; the enantiorecognition power of the other CD derivatives is also being tested. A computational study of model structures to design these CD derivatives.

Alkylation↗
PubMed2004

A survey on high-concentration-capability headspace sampling techniques in the analysis of flavors and fragrances.

This survey critically discusses high-concentration-capacity (HCC) headspace (HS) techniques applied to sample the volatile fraction of matrices of interest in the flavors and fragrance fields. In particular, the advantages, limits, and fields of application of HS solid-phase microextraction (SPME), high-capacity HS sorptive extraction (HSSE) and HS solid-phase dynamic extraction (SPDE) are evaluated. These techniques are discussed in view of the peculiar characteristic of HCC-HS techniques, from the standpoint that these techniques are a bridge between static (S-HS) and dynamic HS (D-HS) because they are as simple, fast, easy to automate, and reliable as S-HS, yet afford analyte concentration factors comparable to those of D-HS. Moreover, the different degree of their development is a consequence of the different times in which they were introduced into the market, because the potential of HS-SPME is now well known, having been introduced approximately 12 years ago, but that of HSSE has still to be fully explored, and HS-SPDE still has to be investigated because it is very recent.

Data Collection↗
PubMed2003

SBSE-GC-ECD/FPD in the analysis of pesticide residues in Passiflora alata Dryander herbal teas.

Stir bar sorptive extraction (SBSE) in combination with GC-ECD/FPD analysis is here applied to the determination of the residues of 11 pesticides (hexachlorobenzene, lindane, chlorothalonil, parathion methyl, parathion ethyl, fenitrothion, malathion, dieldrin, alpha- and beta-endosulfan, and tetradifon) in herbal teas prepared with Passiflora alata Dryander spiked leaves. The method was optimized using spiked herbal teas in a range from 0.05 to 1 pg/microL for organochlorine pesticides and from 0.15 to 3 pg/microL for organophosphorus pesticides. The method is reproducible and repeatable with recoveries calculated from herbal teas prepared with spiked plant material versus spiked herbal teas, varying from about 30% for tetradifon to about 90% for parathion methyl and malathion. The limits of quantitation (LOQs) ranged from 0.017 pg/microL for lindane to 0.117 pg/microL for malathion.

Beverages↗
PubMed2003

(S)-2,3-dihydrofarnesoic acid, a new component in cephalic glands of male European beewolves Philanthus triangulum.

The chemical composition and functional significance of pheromones of solitary Hymenoptera is much less well known compared to social species. Males of the genus Philanthus (Sphecidae) are territorial and scent mark their territories to attract females. Because of inconsistent results of earlier studies, we reanalyzed the content of the cephalic glands of male European beewolves, Philanthus triangulum F. Besides a variety of alkanes and alkenes, four major compounds were found. Two of these, (Z)-11-eicosen-1-ol and (Z)-10-nonadecen-2-one, had been previously described as constituents of the cephalic glands. We identified 1-octadecanol as a new component of the cephalic gland, and a fourth compound, enantiopure (S)-2,3-dihydrofamesoic acid, was identified for the first time in nature. Structural elucidation and enantiomeric analysis were performed by HRGC-MS and HRGC-FTIR as well as enantioselective gas chromatography and by means of authentic reference compounds. Occurrence and function of the four compounds in insect chemistry are discussed.

Animals↗
PubMed2002

Headspace sorptive extraction (HSSE), stir bar sorptive extraction (SBSE), and solid phase microextraction (SPME) applied to the analysis of roasted Arabica coffee and coffee brew.

Headspace sorptive extraction (HSSE) and stir bar sorptive extraction (SBSE), two recently introduced solventless enrichment techniques, have been applied to the analysis of the headspace of Arabica roasted coffee and of the headspace of the brew and of the brew itself. In both HSSE and SBSE enrichment is performed on a thick film of poly(dimethylsiloxane) (PDMS) coated onto a magnet incorporated in a glass jacket. Sampling is done by placing the PDMS stir bar in the headspace (gas phase extraction or HSSE) or by immersing it in the liquid (liquid phase extraction or SBSE). The stir bar is then thermally desorbed on-line with capillary GC-MS. The performance of HSSE and SBSE have been compared through the determination of the recoveries and relative abundances of 16 components of the coffee volatile fraction to classical static headspace (S-HS) and to headspace and in-sample solid phase microextraction (HS-SPME and IS-SPME, respectively) applying the fibers PDMS 100 microm, Carbowax/divinylbenzene 65 microm (CW/DVB), Carboxen/PDMS 75 microm(CAR/PDMS), polyacrylate 85 microm(PA), PDMS/divinylbenzene 65 microm(PDMS/DVB), and Carboxen/divinylbenzene/PDMS 50-30 microm(CAR/PDMS/DVB). In all cases, HSSE and SBSE gave higher recoveries, and this is entirely due to the high amount of PDMS applied.

Chromatography, Gas↗
PubMedDate not supplied

Headspace-solid-phase microextraction fast GC in combination with principal component analysis as a tool to classify different chemotypes of chamomile flower-heads (Matricaria recutita l.).

Headspace-solid-phase microextraction gas chromatography-principal component analysis (HS-SPME GC-PCA) is proposed as a complementary or alternative method to essential oil (EO) GC-PCA in order to discriminate between flower-heads of chamomile of different chemotypes. Ninety-two EOs and the headspaces sampled by HS-SPME of the corresponding chamomile flower-heads were examined by conventional GC and fast GC (F-GC) and the results submitted to statistical analysis by PCA. HS-SPME F-GC-PCA showed itself to be a rapid technique by which to distinguish chamomile flower-head chemotypes a produced results in agreement with the accepted EO classification. Using this method, the analysis time was reduced from at least 4.5 h with EO conventional GC to less than 1 h with HS-SPME F-GC. This approach can thus successfully be used as an analytical decision maker in order to reduce the number of time-consuming EO conventional GC analyses by limiting them to those samples that cannot unequivocally be classified. The EO conventional GC and HS-SPME F-GC results of PCA were very uniform, but they did not provide quantitative correlations between the components as determined by the two methods. A different statistical approach and a larger number of samples will be needed in order to correlate components in the headspace sampled by SPME and those in the corresponding EO quantitatively through a function.

Chromatography, Gas↗