New chiral imidazolium ionic liquids from isomannide.

New chiral bis and mono-imidazolium ionic liquids derived from isomannide were synthesized. The structural features of the chiral organic cations impart a special arrangement of the chiral cavity. The new chiral chloride salts of isomannide derivatives are pivotal compounds for the synthesis of different organic ionic liquids. After metathesis different anions were associated to the chiral cations providing a new class of chiral ionic liquids.

Characterization of the volatile fraction emitted by Pinus spp. by one- and two-dimensional chromatographic techniques with mass spectrometric detection.

The chemical composition of the needles of P. pinea, P. pinaster, P. halepensis, P. nigra, P. brutia, P. patula, P. radiata, P. taeda, P. elliotti, P. kesiya, P. sylvestris and P. eldarica was investigated. Headspace solid-phase microextraction and steam distillation extraction were used to collect the volatile fractions. Samples were analyzed using one-dimensional gas chromatography (1D-GC) and comprehensive two-dimensional gas chromatography (GCxGC) associated with a quadrupole and a time-of-flight mass detectors. Results showed that the analytical capabilities of 1D-GC are partially limited by the separation power of the columns. The higher sensibility and the absence of peak skewing of the time-of-flight mass analyzer, with the use of automated peak finding and deconvolution algorithms, allowed for the detection of trace components with qualitative full spectra and the extraction of true mass spectra from coeluting compounds, promoting their reliable identification and thus significantly improving results obtained by 1D-GC/MS, when using a quadrupole mass analyzer. The use of GC x GC resulted in enhanced separation efficiency and increased signal to noise ratio (sensitivity) of the analytes, maximizing mass spectra quality and improving compound detection and identification. This work shows the use of 1D-GC/ToFMS for the analysis of pine needles volatiles, achieving the detection of 177 compounds, that is more than twice the number previously identified by standard 1D-GC/MS. The analysis by GC x GC for the same sample allowed the detection of 212 compounds. The enantioselective GC x GC analysis performed for all the Pinus spp. under study achieved the detection of 422 different compounds. Cross-over phenomena according to operational conditions are highlighted and discussed.

Comprehensive two-dimensional gas chromatography/mass spectrometric analysis of pepper volatiles.

The headspace compositions of 13 pepper and peppercorn samples of different species, colloquially also referred to as pepper, were analyzed, and more than 300 compounds were tentatively characterized by means of comprehensive two-dimensional gas chromatography in tandem with flame ionization detection, quadrupole mass spectrometric detection and time-of-flight mass spectrometric detection (GC x GC-FID, GC x GC/qMS and GC x GC/TOFMS, respectively). The analysis of volatile organic compounds (VOCs) was performed after solid-phase microextraction (SPME) using a 75-microm PDMS/DVB fibre. Fingerprint comparison between the three techniques permitted peaks to be assigned in the GC x GC-FID experiment based on the analogous MS analysis, taking into account retention shifts arising from method variations. When using GC x GC/TOFMS, about five times more peaks were identified than in GC x GC/qMS. Retention indices for all peaks were calculated in the bi-dimensional column set comprising of a 5% phenyl polysilphenylene-siloxane primary column and a polyethylene glycol second column. The spectra obtained by both mass detection techniques (qMS and TOFMS) give very similar results when spectral library searching was performed. The majority of the identified compounds eluted as pure components as a result of high-resolution GC x GC separations, which significantly reduces co-elution, and therefore increases the likelihood that pure spectra can be obtained. The differences between TOFMS and qMS (in fast scanning mode) spectra were generally small. Whilst spectral quality and relative ion ratios across a narrow peak (e.g. w(b) approximately 100-150 ms) do vary more for the fast peaks obtained in GC x GC/qMS operation, than with TOFMS, in general adequate spectral matching with the library can be achieved.

Characterization of the volatile fraction emitted by phloems of four pinus species by solid-phase microextraction and gas chromatography-mass spectrometry.

Pine forests constitute some of the most important renewable resources supplying timber, paper and chemical industries, among other functions. Characterization of the volatiles emitted by different Pinus species has proven to be an important tool to decode the process of host tree selection by herbivore insects, some of which cause serious economic damage to pines. Variations in the relative composition of the bouquet of semiochemicals are responsible for the outcome of different biological processes, such as mate finding, egg-laying site recognition and host selection. The volatiles present in phloem samples of four pine species, P. halepensis, P. sylvestris, P. pinaster and P. pinea, were identified and characterized with the aim of finding possible host-plant attractants for native pests, such as the bark beetle Tomicus piniperda. The volatile compounds emitted by phloem samples of pines were extracted by headspace solid-phase micro extraction, using a 2cm 50/30mm divinylbenzene/carboxen/polydimethylsiloxane table flex solid-phase microextraction fiber and its contents analyzed by high-resolution gas chromatography, using flame ionization and a non polar and chiral column phases. The components of the volatile fraction emitted by the phloem samples were identified by mass spectrometry using time-of-flight and quadrupole mass analyzers. The estimated relative composition was used to perform a discriminant analysis among pine species, by means of cluster and principal component analysis. It can be concluded that it is possible to discriminate pine species based on the monoterpenes emissions of phloem samples.

Complementary use of hyphenated purge-and-trap gas chromatography techniques and sensory analysis in the aroma profiling of strawberries (Fragaria ananassa).

The aroma compositions of Fragaria ananassa varieties are assessed by purge-and-trap high-resolution gas chromatography. Gas chromatography/mass spectrometry and gas chromatography/Fourier transform infrared spectroscopy allow the identification of 93 components from which 21 are for the first time described as constituents of strawberry aroma. Despite the complexity of the aroma, sensory properties are assigned to 40 components as perceived by three independent testers by application of a sniffing technique to the chromatographic effluent. The data are used for comparative sensory characterization of strawberry varieties by means of principal component analysis.

Bioequivalence assessment of diltiazem preparations by means of discriminant analysis of data from solid-phase extraction and liquid chromatography.

A solid-phase extraction technique for sample clean-up coupled with a new LC procedure is reported for the assay of diltiazem in plasma. The use of disposable cartridges provides selective extraction and easy automation. A new LC system based on LiChrospher RP 60 Select B columns is described. For routine analysis, the procedure provides a rapid simultaneous clean-up of several samples prior to chromatography and reproducible recoveries over a concentration range of 10-800 ng. The procedure was used to analyse the plasma samples from a bioequivalence study of three commercial diltiazem preparations. The pharmacokinetic parameters in 12 healthy male volunteers were determined and the assessment of bioequivalence was conducted by discriminant analysis.