Gas chromatography is an efficient process employed for the separation and determination of various analytes. With the use of a flame ionization detector, gas chromatography can be specifically applied to the chromatographic separation of organic compounds. There are very few processes of analytical study which provide the means to both separate and quantitatively analyze a substance. This useful technique utilized by the chromatographic process allows analytes to disperse from their corresponding mixtures, and subsequently presents an efficient means as to their detection and analysis. This advantageous process allows the detection of various environmental toxins created by incomplete oxidation of hydrocarbon fuels. (Cassalman, et.al 2007) This fractional combustion of hydrocarbon fuels will often result in the production of polycyclic aromatic hydrocarbons and are regarded as significant pollutants in the environment. (Cassalman, et.al 2007) This analysis involves the determination of these polycyclic compounds in a sample by means of three chromatographic methods, and their relative efficiencies with regards to the levels and peak signals of the analyte substances.
[...] The analysis was broken down into three separate courses of action. The final and initial temperature settings were kept equivalent to the temperature programming settings, as this range produced a highly sensitive system. The first 5 minutes of this program was carried out in a manner similar to both the isothermal and temperature programming methods. Analysis of the previous investigations revealed a extremely high resolution after the initial drop down. In order to compensate for this resolution, the rate of temperature increase was amplified from 10(C/min to 13(C/min. [...]
[...] A secondary injection technique employed in gas chromatography is referred to as a split-less injection method. This technique is often applied to sample analysis below of the overall compound. (Harris, 2007) Split- less injection involves the direct injection of the sample into the septum, but as the syringe is withdrawn, compressional forces cause the hole to close and thereby prevent gases from escaping. This system also utilizes a glass liner to ensure that the sample does not directly contact the heated wall, and therefore decreases the possibility of decomposition. [...]
[...] For the duration of the analysis little or no activity occurs until the last few minutes. This response of the detectors elution time, displays a small grouping of varied peak signals towards the end of the analysis. These signals display low resolution characteristics; all clustered within the last remaining minutes. Several of these peaks also appear as duplicates, occupying almost equivalent retention times. This isothermal investigation produced only 5-6 varied elution signals, and therefore was not an efficient method in the determination of the organic compounds. [...]
[...] Each of these methods of analysis yielded results with obvious flaws and inefficiencies. The isothermal investigation displayed very little data, and therefore the test was regarded as an unsuccessful program. The custom program yielded several signals within a suitable resolution, although this increase in resolution resulted in a decreased sensitivity. The decreased sensitivity of the system caused less compounds to appear throughout the analysis and therefore requires improvement. The temperature program, although somewhat less than ideal, produced the most peaks (highest sensitivity) and encompassed a greater spectrum of compounds compared to both the custom and isothermal techniques. [...]
[...] Data: FIG.01 - PAH Gas Chromatography Peak Signals - Isothermal Analysis TABLE.01 - Isothermal Chromatography - Quantitative Analysis GC CONDITIONS PAH NUMBER RETENTION TIME(MIN) HEIGHT(µV) AREA(µV.MIN) He FIG.02 - PAH Gas Chromatography Peak Signals - Temp Alterations TABLE.02 - Temperature Programming - Quantitative Analysis GC CONDITIONS PAH NUMBER RETENTION TIME HEIGHT (µV) AREA (MIN) (µV.MIN) Range: FIG.03 - PAH Gas Chromatography Peak Signals - Custom Program TABLE.03 - Custom Program - Quantitative Analysis GC CONDITIONS PAH NUMBER RETENTION TIME HEIGHT (µV) AREA (µV.MIN) (MIN) TABLE.04 - Custom Program Specifications / Parameters SPECS STAGE INITIAL RATE FINAL TEMP TIME (MIN) TEMP((C) Volume: Results/Discussion: The analysis of these organic compounds involved the utilization of various programming techniques, with respects to the parameter settings of the gas chromatograph. [...]
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