Cryogenic-zone-compression gas chromatography-mass spectrometry for the determination of 16 polycyclic aromatic hydrocarbons in extra virgin olive oil

The present study is based on the development of a straightforward method for the determination (semi-quantification) of 16 polycyclic aromatic hydrocarbons (PAHs) in extra virgin olive oil (EVOO) using "cryogenic-zone-compression" (CZC) gas chromatography-single quadrupole mass spectrometry (GC-QMS). The use of CZC (through a loop-type cryogenic modulator) to achieve enhanced signal-to-noise ratios (s/n), enabled a simplification of the sample preparation step. In fact, a single extraction process (using only 500 µL of acetonitrile) was performed prior to injection. The CZC GC-QMS method aligns with the principles of green analytical chemistry, and enabled an average s/n increase of 14-fold compared to conventional GC-QMS. The method limits of quantification were in the 0.07-8.33 µg kg-1 range. Accuracy (at the 2 μg kg-1 and 10 μg kg-1 concentration levels) was in the 82-103 % range. Intra-day and inter-day precision (at 2 μg kg-1 and 10 μg kg-1 concentration levels) were in the 1.9-14.7 % and 5.9-9.1 % ranges, respectively, while the recovery values (at 10 µg kg-1) ranged from 24 % to 99 %. For all the PAHs investigated, a positive matrix effect was observed. Two PAHs were detected (in the selected-ion-monitoring mode) in six EVOOs among the ten samples (not more than one PAH per sample).

Methods of discovery-based and targeted metabolite analysis by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection

The investigation of naturally volatile and derivatized metabolites in biological tissues by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) can provide highly complex and information-rich data for comprehensive metabolomics analysis. The addition of the second separation dimension with GC × GC provides additional chemical selectivity, and the fast scanning time of TOFMS offers benefits in chemical selectivity and overall peak capacity compared to traditional one-dimensional (1D) GC. Furthermore, methods of derivatization to facilitate volatility and thermal stability, the most prominent being the silylation of organic compounds, have extended the use of GC as an important metabolomics tool. The highly information-rich data from GC × GC-TOFMS benefits from sophisticated comprehensive targeted and nontargeted algorithmic software methods. Herein, we detail a robust derivatization and instrumental method for metabolomics analysis and provide a brief overview of possible methods for data analysis.

Short column gas chromatography-mass spectrometry and principal component analysis for the identification of coeluted substances in doping control analysis

The identification of four doping control substances in an artificial mixture, using short column gas chromatography-mass spectrometry (GC-MS) analysis was examined. Two chromatographic peaks were recorded in the chromatogram, using a short capillary column (1.8 m) at an oven temperature of 180 degrees C. The first peak was associated with a mixture of a solvent derivative and an artifact. The second one corresponded to the mixture of four control substances. Principal component analysis was applied on a selected GC-MS data set of the latter peak to determine clear full spectra of pure substances from mixture spectra. The time of GC-MS analysis was significantly reduced to less than 1 min from 30 min which is a typical GC-MS analysis time, using standard methods of doping control analysis.