Volatile compounds identification

The volatile compound identification was carried out by injecting 2 pi of diluted extract (200 pi oil + 1500 pi hexane) into a Hewlett - Packard Gas Chromatograph- Mass Spectrometer (GC-MS) equipped with a HP-1 capillary column. Injector temperature was maintained at 250 °C. Column temperature was kept at 100 °C for 4 min and programmed from 100 °C to 250 °C at 7 °C/min. N2 at the flow rate of 0.543 ml/min was used as a carrier... 

Pork meat (loin) and subcutaneous fat from one outdoor-reared Iberian pig were purchased from a local slaughterhouse. L-cysteine, L-proline (Sigma-Aldrich), sodium chloride (Scharlau), and sodium nitrite (Scharlau) were used. The reference compounds for volatile compound identification were obtained from Sigma-Aldrich. 

Identification of the Volatile Compounds. Identification of the volatile compounds was accomplished by comparing the mass spectral data with those of authentic compounds available from the Browser-Wiley computer library, NBS computer library or previously published literature 10-14,22). The retention indices (using a C5-C25 mixture as a reference standard) were used for the confirmation of structural assignments. 

The identification of volatile compounds of both Mo and W in gases from a municipal landfill (Feldmann and Cullen 1997) illustrated unusual transformation products. Although these compounds were tentatively identified as Mn2(CO)jo and W(CO)g, neither the mechanism of their formation nor their potential health hazards has been resolved. 

Most of the studies on the thermal degradation of carotenoids analyzed the volatile fraction, as the identification of nonvolatile fractions was probably more complex to analyze. A study was published recently on the volatile compounds generated by the thermal degradation of carotenoids in... 

The second, more theoretical approach is based on the chemical analysis of the volatile compounds which are emitted. The scope is to find and to identify one or more volatile compounds which are specific for the current status of the cooking process. A possible disadvantage of this approach is that after the identification of volatile components it cannot be assured that suitable gas sensors are available or can be developed. 

Novotny, M.V., Soini, H.A., Koyama, S., Wiesler, D., Bruce, K.E. and Penn, D.J. (2007) Chemical identification of MHC-influenced volatile compounds in mouse urine. I Quantitative proportions of major chemosignals. J. Chem. Ecol. 33, 417—434. 

This is an alternative technique to headspace analysis for the identification and determination of volatile organic compounds in water. The sample is purged with an inert gas for a fixed period of time. Volatile compounds are sparged from the sample and collected on a solid sorbent trap—usually activated carbon. The trap is then rapidly heated and the compounds collected and transferred as a plug under a reversed flow of inert gas to an external gas chromatograph. Chromatographic techniques are then used to quantify and identify sample components. 

Tang J, Jin QZ, Shen GH, et al. 1983. Isolation and identification of volatile compounds from fried chicken. J Agric Food Chem 31 1287-1292. 

Yasuhara A. 1987. Identification of volatile compounds in poultry manure by gas chromatography-mass spectrometry. J Chromatogr 387 371-378. 

Coleman, E. C., Ho, C. -T., Chang, S. S. (1981). Isolation and identification of volatile compounds from baked potatoes. Journal of Agricultural and Food Chemistry, 29,42 8. 

Sampling and Analysis. A frozen slice of bread was cut in pieces and stacked in an enlarged sample flask of an aroma isolation apparatus according to MacLeod and Ames (74). Volatile compounds were trapped on Tenax TA and afterwards thermally desorbed and cold trap injected in a Carlo Erba GC 6000 vega equipped with a Supelcowax 10 capillary column (60 m x 0.25 mm i.d.) and a flame ionisation detector. Similar GC conditions were used for GC-MS identification of volatile compounds by dr. M.A. Posthumus (Dept. Organic Chemistry, VG MM7070F mass spectrometer at 70 eV El, 75). 

H. Maarse, R. Belz, Isolation, Separation and Identification of Volatile Compounds in Aroma Research, Akademie-Verlag, Berlin 1981. 

In the identification experiments, the GC and MS data of the analytes have to be compared with those of corresponding authentic samples. However, as mentioned already, odorants are often concealed in the gas chromatogram by major volatile compounds therefore, to avoid misidentification it is necessary to compare by GC-O the odour quality of the analyte with that of the authentic sample at approximately equal levels. The analyte, which has been perceived by GC-O in the volatile fraction, is only correctly identified if there is agreement in the sensorial properties, in addition to GC and MS data. 

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