Gas chromatography, under chromatographic separation method, takes advantage of the volatility of the sample constituents (Punrattanasin and Spada). This separation technique is utilized for both quantitative and qualitative analyses. As such, gas chromatography can separate solutes of wide temperature-range by sample vaporization from lowest to higher temperatures sufficient for the elution of constituents with high boiling points (Tissue). In connection to this, gas chromatography is employed in the separation of volatile constituents of any mixture (Scott 68).
Also, non-volatile biomolecules like fatty acids, amino acids, and steroids can be induced to form volatile derivatives for gas chromatographic analysis (Scott 68). Meanwhile, gasoline analysis is the most typical subject of gas chromatography. Gasoline is a multi-component mixture of hydrocarbons with relatively similar boiling points; thus, call for a separation technique which is boiling point sensitive (Scott 68). For this experiment, fire debris will be analyzed for accelerant determination. Two carpet samples will be set into fire, whereas accelerant will be applied on one carpet while the other will spontaneously be burned.
Then, Gas Chromatography coupled with Mass Spectroscopy will be employed for identification of fire debris attributes caused by arson. Basic Principles A typical gas chromatographic system has injection port, gaseous mobile phase, column of stationary phase, detector, and data recorder (Tissue). The volatile sample is introduced into a rubber septum for heating and vaporization. Then, the mobile phase or carrier gas such as hydrogen, nitrogen or helium transports the vaporized sample into the column that separates the vapor into gaseous components (Harris 313).
The solute vapor dissolved in a gaseous mobile phase passes through the stationary phase in a long and thin column (Harris 313). Then, the sample constituents separate within the solid or liquid stationary phase though the gaseous mobile phase; thus facilitating the separation of the sample into its components (Punrattanasin and Spada). After this, the detector decodes the identity of each gaseous constituent which in turn display by the computer as chromatogram (Harris 313). In addition, the column must maintain a temperature well-suited for vaporization of the sample so as to generate enough vapor pressure for each component (Harris 313).
Similarly, the detector is also maintained at a temperature higher than the column to ensure gaseous solutes. Further, 0. 5-10 milliliter of gaseous sample can be injected into the system by means of a valve or gas-tight syringe (Harris 313). Nevertheless, for analytical chromatography, 0. 1-2 microliter liquid sample can be introduced into the system as the column can possibly handle 20-1000 microliter injected samples (Harris 313). Figure 1. Schematic Diagram of Gas Chromatographic System (Punrattanasin and Spada). Works Cited Harris, Daniel. Exploring Chemical Analysis.
New York: W. H. Freeman and Company, 1997. Punrattanasin, Warangkana and Spada, Christine. “Gas Chromatography. ” 10 September 1997. Environmental Sampling and Monitoring Primer. 3 March 2009 <http://www. cee. vt. edu/ewr/environmental/teach/smprimer/gc/gc. html> Scott, Raymond P. W. “Chrom-Ed Book Series, Principles and Practice of Chromatography. ” 2003. Library 4 Science. 3 March 2009 <http://www. chromatographyonline. org/members/form. html> Tissue, Brian M. “Gas Chromatography. ” June 2003. Chemistry Hypermedia Project. 3 March 2009 < http://www. files. chem. vt. edu/chem-ed/sep/gc/gc. html>.