Gas liquid chromatography

a type of chromatography usually used to analyze pollution aspects.

1. GAS LIQUID CHROMATOGRAPHY By Anand Narayanan D FEN-2018-33-01

2. CHROMATOGRAPHY Chromatography is an analytical technique where in a sample mixture under test is separated into different components based on difference in their affinity for a stationery phase and mobile phase.

3. GAS LIQUID CHROMATOGRAPHY(GLC) In GLC the mobile phase is an unreactive gas , such as nitrogen(Carrier gas). The stationery phase is a non volatile liquid held on a finely divided inert solid support.

4. PRINCIPLE Gas liquid chromatography runs on the principle of partition. In GLC , components of the gaseous samples are separated due to partition between a gaseous mobile phase and a liquid stationery phase held in a column.

5. The mobile phase An inert gas such as He or N2 -Function is to transport sample vapours through columns. -No chemical interaction with sample. Typical parameters -column inlet pressure : 10-50psi -flow rate 25-50mL/min Precise control of carrier gas flow rate is crtical to obtain reproducible retention times .

6. Sample injection Sample is injected using a syringe into a hot carrier gas(mobile gas) -High temperature( at least 50 ͦC above B.P of sample) causes vaporization of sample. - introduced a narrow plug of sample vapour onto the column. Various designs -for packed columns , inject 1 to 5 microliters of sample. -for capillary columns , a split valve is used to introduce a small fraction sample into the column .

7. Detectors Generate an electrical signal proportional tp solute concentration or mass flow rate. Ideal characteristics : High sensitivity Rapid response time Applicable to wide range of samples Easy to use Stable & predictable response

8. RECORDER Recorder is device that draws the chromatogram that results from a chromatographic process on to chart paper. The time scale of the chart movement normally ranges from about 1cm/ second to 1cm / hour

9. Advantages of GLC Both qualitative and quantitative analysis are possible. Instrument is simple , time of analysis is short. High sensitivity This method is applicable for 60% of organic compounds Very small sample sizes can be used Analysis can be highly accurate and precise.

10. FACTORS AFFECTING SEPERATION Particle size and surface area Carrier gas flow rate Type and amount of stationery phase Column length Column diameter Column temperature

11. CONCLUSION Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition . The sample being measured is injected into the carrier gas using a syringe and instantly vaporizes (turns into gas form). The gases that make up the sample separate out as they move along the column which contains the stationary phase

12. REFERENCES Introduction and principle of GLC , by Dr.Vishnu Vrardhan R eddy P ulimi , www.slideshare.net Gas liquid chromatography by Srinivas Nandyala , m.athorstream.com