Gas Chromatography

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group 2Gas Chromotography Mass SpectrumLab ManualNOrth Carolina A&T State University chemistry DepartmentPatrick Mills Erin Barnes| |
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January 24, 2013
Introduction:
Chromatography is the separation of components of a mixture by differential adsorption between a stationary phase and a mobile phase.1 GC separates molecules as it moves through the column. There are two different column types that are used in gas chromatography, packed and capillary.3 The detector is connected to a recording device, which shows a deflection when a sample passes the detector in proportion to the amount of sample detected. Compounds are eluted through an exit port either in an intact form or as combustion products, depending upon the type of detector used. The substances is pushed a carrier gas along 30m of column and the mass spectrum records the peaks, floating electrons, as they travel through the vacuum. 1mL/min of Helium is used as the carrier gas. GC uses a detector to measure the components of different compounds and records the retention time which is used to determine the compound.3 The mass spectrum (MS) is a graph produced which scientist then analyzes to determine the mass. MS also gives information about the complexities of molecules.1 MS can be used in combination with other spectroscopic methods to elucidate structure.1 Table of Physical Constants:

Data Table:
Substance| Molecular Weight (g/mol)| Reference Melting Point (C)| Reference Boiling Point (C)| Density (g/ml)| Color/State| o-Xylene| 106.16| -47.87- 13.26| 140| .87| White/pellets| Toluene| 92.14| 158-160| 110.62| .86| Colorless-white/crystals| Cumene| 120.19| -| 152.39| .81| Colourless /liquid|

Dichloromethane| | | | | |
Procedure:
Students diluted solution of o-Xylene (gm), Toulene (gm), and Cumene (gm). A drop of each was added to a GC vial. Dichloromethane (1mL) added and students shook the vial. The GC vials containing the...
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