Principles of Gas- Chromatography (GC)

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1 Principles of Gas- Chromatography (GC) Mohammed N. Sabir January Jan-17 1

2 GC is a chromatographic technique utilizes gas as the mobile phase which is usually an inert gas (Hydrogen, Helium, Nitrogen and Air). 10-Jan-17 2

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4 GC has wide applications in many fields including NPs, chemistry, pharmaceuticals, medicine, agriculture, biology, etc. 10-Jan-17 4

5 GC is most applicable for volatile substances and lipids. 10-Jan-17 5

6 Although It is very expensive; GC is precise, accurate, delicate, rapid and applicable to a wide range of chemical substances. 10-Jan-17 6

7 We have two types of GC: GLC (Gas-liquid chromatography). Here we have partition since the mobile phase is gas and the stationary phase is a thin layer of a non-volatile liquid bound to a solid support. 10-Jan-17 7

8 The other is GSC (Gas- Solid chromatography). Here we have adsorption since the stationary phase is a solid adsorbent (It is based upon selective adsorption of sample on a solid surface). 10-Jan-17 8

9 GC consists of six basic components: A carrier gas which is maintained at a high pressure and is delivered to the instrument at a rapid and reproducible rate. A sample injection system. The separation column. One or more detectors. Thermostat chambers for the temperature regulation of column and detectors. An amplification and recorder system. 10-Jan-17 9

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13 There are two types of GC-columns Packed columns. Capillary columns. 10-Jan-17 13

14 The carrier gas should be:- Inert, not react with the sample, stationary phase or hardware. Have low density. High flow rate, Inexpensive. Good thermal conductivity. Suitable for the detector employed and type of sample to be analyzed. Readily available in high purity. None explosive and none hazardous. 10-Jan-17 14

15 Separation takes place when the gas (mobile phase) will flow at certain rate under specified temperature and pressure through the column which contains the fixed (stationary phase). 10-Jan-17 15

16 The sample mixture is injected through the injector and will be carried by the gas (mobile phase) through the column. The sample should be either liquefied or dissolved in a suitable solvent. 10-Jan-17 16

17 Each compound will be retained on the stationary phase according to its preferences to the phase. 10-Jan-17 17

18 When retained the compound will be delayed, different compounds have different electronic environments; therefore they will be retained by the stationary phase and reaches the detector at different times. 10-Jan-17 18

19 Upon reaching the detector, they will be expressed in form of peaks with different intensities and diameters correspondent to the compound and its concentration in the mixture. 10-Jan-17 19

20 It is preferable that the GC will be connected to another device that will diagnose the chemical nature of the compounds separated by the GC. 10-Jan-17 20

21 So we have GC-MS (connected to a Mass spectrometer which will give the mass molecular weight of the separated compound. 10-Jan-17 21

22 In both HPLC and GC, there are factors that affect the retention time of the chemical compound as:- Temperature (affects the solubility, volatility and elution process). Time of running and volume of the mobile phase. 10-Jan-17 22

23 In many cases sample preparation and derivatization may be needed to achieve optimum separation process. 10-Jan-17 23

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25 Diagrammatic representation of GC chart. 10-Jan-17 25

26 A GC chart. 10-Jan-17 26

27 Physical detection for the sample is made by coupling of the GC instrument to a spectrometer like IR or Mass spectrometers. 10-Jan-17 27

28 Addition of spectrometers to the system enables better characterization and identification of the sample in the mixture and faster running time. 10-Jan-17 28

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30 Review of the lecture Any questions? Thanks for listening 10-Jan-17 30

Gas Chromatography. Presented By Mr. Venkateswarlu Mpharm KTPC

Gas Chromatography. Presented By Mr. Venkateswarlu Mpharm KTPC Gas Chromatography Gas Chromatography Presented By Mr. Venkateswarlu Mpharm KTPC What is Gas Chromatography? It is also known as Gas-Liquid Chromatography (GLC) GAS CHROMATOGRAPHY Separation of gaseous