PubMed · 4840583
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A F Haeberer, W S Schlotzhauer, O T Chortyk. A rapid quantitative method for maleic hydrazide.. https://doi.org/10.1021/jf60192a043
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Supercritical fluid carbon dioxide extraction (SFE) has been evaluated for the extraction of 17 organohalogen and organophosphate pesticides in gazpacho (a table-ready food composite containing crude vegetables, white bread, vegetable oil, water, and other minor components) using anhydrous magnesium sulfate as drying agent. The effects of different parameters, such as fat content in gazpacho composites, magnesium sulfate/gazpacho ratio, supercritical fluid volume, pressure, temperature, and static modifier additions, on SFE recoveries from spiked gazpacho samples have been studied. Analyses were performed by gas chromatography (GC) with flame photometric (FPD), electron capture (ECD), and mass spectrometry (MSD) detectors. In most experiments, recoveries obtained for the nonpolar organohalogen pesticides were lower than those obtained for the most polar organophosphate pesticides, but overall pesticide recoveries determined by using the optimal SFE conditions indicate that SFE could be used to determine pesticide residue levels in gazpacho.
This investigation concerns the application of fast GC in the analysis of essential oils. These are complex matrixes that usually undergo GC separation with conventional methods involving long columns, slow programmed temperature rates, and consequently, a high cost in terms of time. Fast GC techniques are based on the use of narrow bore capillary columns that allow the achievement of high-speed separations on complex samples while maintaining excellent resolution. This work saw the application of two methods on five different citrus essential oils and the comparison of all the results obtained.
Gas-liquid chromatography was applied to investigate the mechanism of alpha-cyclodextrin (alpha-CD) complexation processes with some chiral monoterpenoids differing from each other in chemical properties and structure. They were chosen from hydrocarbons, alcohols, aldehydes and ketones of acyclic, monocyclic and bicyclic structure. The relationships between the retention factor, k, of a guest solute (G) and alpha-CD concentration were studied. The obtained data enabled the stoichiometry, the stability of individual complexes and the separation factor of enantiomers to be determined. It was found that almost all the investigated monoterpenoids, apart from the acyclic ones, form inclusion complexes with alpha-CD. Straight-line relations (r vs. [alpha-CD]) were observed for monocyclic alcohols and pulegone, without any trace of enantioselectivity. This behaviour indicates that the 1:1 stoichiometry of the G-CD complexes does not lead to chiral recognition. Parabolic relations arising from 1:2 stoichiometry were found for limonene, alpha-phellandrene, some monocycylic ketones and all the investigated bicyclic terpenoids. It appeared that only the second step of complexation displayed marked enantioselectivity. However, a loss of efficiency resulting from slower equilibration is then noticeable. Attempts are made to rationalize the chromatographic results with respect to the structure of the investigated compounds.