Gas Chromatography (GC) (IUPAC Compendium of Chemical Terminology):
Lecture 3. Gas chromathography. Application area and Instrumentation. Mobile phase: carrier gas. He, N 2 , H 2, CO 2 , Ar. The carrier gas must be chemically inert. The choice of carrier gas is often dependent upon the type of detector which is used. The carrier gas system also contains a molecular sieve to remove water and other impurities. Stationary phase: nonvolatile liquid, sometimes solid. Two kinds of column are used: packed and open tubular (capillary). Packed columns contain a finely divided, inert, solid support material (commonly based on diatomaceous earth) coated with liquid stationary phase. Most packed columns are 1.5 - 10m in length and have an internal diameter of 2 – 4mm. Capillary columns have an internal diameter of a few tenths of a millimeter. The inner walls are coated with thin layer of stationary phase. Analyte: gas or volatile liquid. Hydrocarbons, fatty acids, flavor compounds, essential oils, environmental pollutants (pesticides), especially modified substances. It is estimated that 10-20% of the known compounds can be analyzed by GC. To be suitable for GC analysis, a compound must have sufficient volatility and thermal stability. If all or some of a compound or molecules are in the gas or vapor phase at 400-450°C or below, and they do not decompose at these temperatures, the compound can probably be analyzed by GC. Flow controller Injection port Recorder Carrier gas Column oven Detector 2
Lecture 3. Gas chromathography. Advantages of GC ● ● ● ● ● non-destructive method of analysis; analysis is fast; analysis is sensitive; high resolution; method is compatible with many types of detectors, including MS. Drawbacks of GC ● ● suitable mostly for analytical purposes; restricted choice of eluent “polarity”; Variable parameters in GC: ● ● ● ● column; carrier gas; gas flow rate; temperature. 3
- Page 1: Lecture 3. Gas chromathography. Gas
- Page 5 and 6: Film thickness, μm Lecture 3. Gas
- Page 7 and 8: Lecture 3. Gas chromathography. POL
- Page 9 and 10: Lecture 3. Gas chromathography. Non
- Page 11 and 12: Lecture 3. Gas chromathography. 11
- Page 13 and 14: Lecture 3. Gas chromathography. Col
- Page 15 and 16: Lecture 3. Gas chromathography. Eff
- Page 17 and 18: Lecture 3. Gas chromathography. GAS
- Page 19 and 20: Lecture 3. Gas chromathography. Tem
- Page 21 and 22: Lecture 3. Gas chromathography. Sam
- Page 23 and 24: Lecture 3. Gas chromathography. Spl
- Page 25 and 26: Lecture 3. Gas chromathography. Com
- Page 27 and 28: Lecture 3. Gas chromathography. Pur
- Page 29 and 30: Lecture 3. Gas chromathography. Der
- Page 31 and 32: Lecture 3. Gas chromathography. Rea
- Page 33: Lecture 3. Gas chromathography. 33
Lecture 3. <strong>Gas</strong> chromathography.<br />
Advantages <strong>of</strong> <strong>GC</strong><br />
●<br />
●<br />
●<br />
●<br />
●<br />
non-destructive method <strong>of</strong> analysis;<br />
analysis is fast;<br />
analysis is sensitive;<br />
high resolution;<br />
method is compatible with many types <strong>of</strong> detectors, including MS.<br />
Drawbacks <strong>of</strong> <strong>GC</strong><br />
●<br />
●<br />
suitable mostly for analytical purposes;<br />
restricted choice <strong>of</strong> eluent “polarity”;<br />
Variable parameters in <strong>GC</strong>:<br />
●<br />
●<br />
●<br />
●<br />
column;<br />
carrier gas;<br />
gas flow rate;<br />
temperature.<br />
3
Change language