Injector port: A place where the liquid sample is vaporized and transported onto the column by the carrier gas

Carrier gas: To move the solutes through the column

Detector: To detect components of the mixture being eluted off the chromatography column

Column: It is responsible for the separation process

Computer:  To generates a graph from the

·         Gas carrier & regulators

·         Gas lines to remove moisture and contaminants from incoming gases

 

2)      INJECTION PORT

·         Provide place for sample introduction, vaporization, dilution & splitting.

 

3)      OVEN

·         Controls temperature

·         Interaction of analyte with stationary phase and the boiling point for separation of compounds.

·         Column & stationary phase

·         Capillary column

 

4)      DETECTORS

·         Thermal conductivity: detects almost anything

·         Flame ionization: detects organics

·         Electron capture: halogenated compounds and those with nitro or conjugated double bonds

·         Flame photometric: specific compounds with S & P

·         Photoionization: ionization energy of lamp relative to bond energy of solutes

·         Used forensically in drug analysis and toxicology analysis

·         Detect and measure contaminants from spoilage

1) GC SCHEMATIC DIAGRAM

        i.  Carrier Gas – used to move the solutes through the column.

       ii. Gas Flow Regulator -to assure a constant flow through the column and detector independent of the type of gas, the temperature and the column dimensions.

     iii.   Injector Port -a port used for injecting the samples into the GC or necessary for introducing the sample at the head of the column.

     iv. Column oven –to control the temperature of the column within a few tenths of a degree to conduct precise work.

       v. Column – used to separate analyte into individual component.

     vi. Detector- provides a quantitative measurement of the components of the mixture as they elute in combination with the carrier gas.

 .  GC is used in the analysis of air borne pollutants, performance-enhancing drugs in athelet’s urine samples, oil spills and essential oils in perfume preparation.

·       Gas Chromatography is used extensively in forensic science. Disciplines as diverse as solid drug dose identification and quantification.

·       GC analysis used to calculate the content of a chemical product for example in assuring the quality of product in the chemical industry or measuring toxic substances in soil, air and water.

1. GC Schematic Diagram

2. Functions of each component in GC.
(a) Gas supply system 
– To help in moving the samples through the column.

(b) Gas flow regulator (flow controller) 
– To facilitate smooth flow of the gas supplied.

(c) Molecular sieve traps 
– To remove other substances such as oxygen and hydrocarbon from the flowing gas.

(d) Fixed restrictor 
– To restrict the flow of carrier gas.

(e) Injection port 
– To vaporize the sample and injected into the column with the help of gas.

(f) Column 
– To separate the sample injected.

(g) Oven 
– To control the temperature of the column.

(h) Detector 
– To detect sample being eluted off the column.

(i) Electrometer 
– To detect electrical signals generated from the detector.

(j) Recorder/Integrator 
– To generate a chromatogram based on the signals received.

 3. Application of GC

Analysis for 

(a) airborne pollutants

(b) oil spills

(c) drugs presented in urine samples

(d) essential oils in perfume production

(e) pesticide residue in food

(f) detection of volatile component

 

Sample injection: introduced the sample at the head of the column, a calibrated microsyringe is used to deliver a sample volume in the range of a few microliters through a rubber septum and into the vaporization chamber

Carrier gas: carrier gas must be dry, free of oxygen and chemically inert- mobile phase employed gas chromatography. 

Column oven: the oven can be operated in two manners; isothermal programming/ temperature programming. In isothermal programming, the temperature of the column is held constant throughout the entire separation while in the temperature programming method, the column temperature is either increased continuously or in steps as the separation progress.

Open tubular columns/packed columns: open tubular columns, which are also known as capillary columns, come in two basic forms- the first is wall-coated open tubular(WCOT) column and the second type is support-coated open tubular(SCOT) column. WCOT columns are capillary tubes that have a thin layer of the stationary phase coated along the column. For SCOT columns, the column walls are first coated with a thin layer of adsorbant solid, the solid is then treated with the liquid stationary phase. 

Detector systems: The detector is device located at the end of the columns which provides a quantitative measurements of components of the mixtures as they elute in combinations with carrier gas. Each of the detector has two main parts that when used together they served as transducers to convert the detected property changes into an electric signal that is recorded as a chromatogram.

2.       State any application of GC that you know: 

Food analysis: GC is used for the analysis of food additives, component of flavour and aroma. It is also used for the detection and analysis of contaminants such as pesticides. 

Forensics application: GC is used to detect the circumstances of a person’s death whether by ingested poison, drugs or overuse of alcohol.

1. SCHEMATIC DIAGRAM OF GAS CHROMATOGRAPHY

(d) Fixed restrictor 
– Restricts the flow of gas

(e) Injection port 
– Helps in vaporizing the sample 

(f) Column 
– Aid in sample separation

(g) Oven 
– To control temperature within the column

(h) Detector 
– Detects sample eluted of the column and quantifies them, sends signals

(i) Electrometer 
– Receives signals from the detector 

(j) Recorder/Integrator 
– Generates a chromatogram based on the signals

3)APPLICATION OF GC
- Measuring Air Pollution
- Qualitative and quantitative food analysis
- Forensics (finding the cause of victim's death through body liquid compositions)
- Analyzing soil samples from Mars

For qualitative and quantitative analysis of food residues, gas chromatography-mass spectrometry (GC-MS) is an important application in food analysis and technology. In the field of food analysis, multidimensional techniques such as comprehensive GC can give unrivalled resolving power for extremely complex combinations, and narrow-bore columns can achieve very quick separations in the second dimension. 

A carrier gas is used to separate the components, and this gas serves as the mobile phase. The carrier gas in the chromatography moves the sample molecules through the GC system without interacting with the sample or causing damage to the instrument components.

Used to measure the carrier gas flow so the gas flow rate remains constant in the whole process.

To deliver the gas with uniform pressure of flow rate required.

It has uses in the system to filter out water and other contaminants. This is for keeping the system clean and sensitive by removing water and other impurities.

The place of the sample is injected through the septum into a heated chamber containing a glass liner in the injector.

When the analysis requires an isolated column, the fixed restrictor valve is typically used to replicate an installed column, or for specific liquid or gas sample applications that require a regulated pressure.

One of the components for measuring very low voltages and currents Ionization detector currents must be measured with an electrometer.

To work properly, the interaction detected by the detector is converted into an electronic signal by the detector, which is then supplied to the data system.

Within the column, the stationary phase is where separation can occur. A mobile phase passes through a separation column on its way to a detector.

In gas chromatography, recorders are used to record the response acquired from the detectors after amplification. Generally, a detector used to get through the input response is continuously balanced by the feedback response in this sort of recorder.

Refer to the attachment below. 

2. Function(s) of each components

a) Gas supply and regulators- to supply gas and it serve as the mobile phase in the GC. Common carrier gas used are argon, nitrogen and helium. While regulator controls the pressure and flow control.  

b)  Injection port- it provides a place for sample introduction. The sample is introduced into the injection port by using a manual syringe or automated sampling system. 

c) Oven- it controls the temperature of column, and it also helps the interaction of analyte with stationary phase and the boiling point for separation of compounds. 

d) Column- place where separation occur, sample injected undergo separation. 

e) Detector- to detect the sample eluted and electrical signals are produced which is then supplied to the recorders. 

f) Electronics & recorder/data handling system- Generate chromatogram based on the signal produced. 

3. Application of GC
- In food industry: good choice for most food work as majority food are organic compound. It helps in the flavour studies, fatty acid analysis, carbohydrate analysis, sterols, contaminants in food and antioxidants. 

- In forensic science: GC is used to determine the circumstances of a person’s death, whether the deceased person has taken any alcohol or drugs before death, as well as to determine whether the person ingested poison. It can also be used in analysis of trace evidence in the crime scene for example, the fibres in the carpet, polymers in paint to help put the facts and evidence together. Also, it can also determine the blood alcohol level that impaired their normal functioning and also determine at the time of death. 

FUNCTION OF EACH COMPONENTS.
a) gas flow regulator- to control flow and pressure of gas input
b) gas supply system- to supply carrier gas that moves the sample through the column
c) injection part- to place the sample and change sample to gas.
d) column- to separate sample
e) oven - to control temperature of the column
f)detector- to detect the different compounds.
g) recoder- to give an output in a form of electrical signal.

1.     Carrier gas 

To transfer the injected sample to the separation column and subsequently transfer the separated components to the detector.

Examples: Nitrogen, Helium, Hydrogen (high purity & chemically inert)

 

2.     Sample injection port

To provide a place in which sample is injected either by a gas-tight syringe or with the help of automated injection valves at an elevated temperature. The common volume of samples injected ranges from 0.1 to 0.2 ml.

 

3.      Oven

To enclose the column and is used to help in controlling the temperature of the column.

It can be operated in two ways, which are isothermal programming and temperature programming. For isothermal programming, the column’s temperature during the whole separation process is constant. On the other hand, temperature programming allows the column’s temperature to increase continuously or in steps during the separation process.

 

4.     Column

To contain the stationary phase and provide a passing way for the mobile phase.

A place where the separation process occurs.

Two common types: packed column & capillary column

 

5.     Detector

To identify and quantify the components by sensing their arrival once they eluate from the column.

The most common detector used is Flame Ionization Detector (FID).

 

6.     Recorder 

To record the response obtained in the form of baseline and peaks obtained over time from the detector after amplification. 

Integrator can be added to improve the function of a recorder by giving more information on the peaks.

 

1.     Used in the quantitative and qualitative analysis of food to ensure the safety of the food products.

2.     Used in the quality control in pharmaceutical industry for production of pure products in large quantity.

3.     Used in the analysis of air-borne pollutants to solve the air pollution problem.

 

·         Gas supply system – supplies gas

·         Injection port – used to introduce samples using a manual syringe technique or an automated sampling system

·         Oven – controls the temperature of the column

·         Column – used to analyze samples for the individual chemical compounds

·         Detector – used to detect components in the mixture that is being eluted in the column

·         Electronics & recorder/data handling system – used to create chromatogram 

Applications of GC

Used in :

·         Food analysis

·         Quality control

·         Blood alcohol analysis

·         Measuring air pollution

·         Industrial hygiene

·         Pharmaceutical

·         Life science industry

- Supply and regulate gas

2. Injection port

-  For sample introduction by the injection port using manual syringe

3.  Oven

- Control the temperature of the column 

4. Column

- For the separation of the sample

5. Detector

- Detect the components in the sample

6. Data handling system

- Shows the result of the sample analysis injected

- Use for the analysis of sterols, oils, low chain fatty acids, aroma components and many other contaminants.

- In pharmaceutical industry, GC is use to detect impurities in products.

1.    Gas supply system

To transport the injected sample to the separation column and then to the detector with the separated components.

2.    Injection port

To provide a location where a sample is injected at a higher temperature using a gas-tight syringe or automated injection valves.

3.    Column oven

The oven has two modes of operation: isothermal programming and temperature programming. The temperature of the column is kept constant during the separation in isothermal programming, whereas the temperature of the column is either increased continuously or in increments as the separation progresses in temperature programming.

4.    Sample injector

A calibrated micro syringe is used to transport a sample volume in the range of a few microliters via a rubber septum and into the vaporization chamber once the sample is placed at the head of the column.

5.    Recorder/Integrator

After amplification, the response from the detector is recorded in the form of a baseline and peaks over time.

6.    Detector 

By sensing their arrival once they elute from the column, the components can be identified and quantified.

7.    Flow controller

The carrier gas flow is measured so that the gas flow rate remains consistent throughout the procedure.

 

Application of GC:

Gas chromatography is a physical separation technique that separates volatile mixtures. It has applications in a variety of sectors, including pharmaceuticals, cosmetics, and even environmental hazards. Because the samples must be volatile, GC can easily examine human breath, blood, saliva, and other fluids containing substantial volumes of organic volatiles. GC also can be used to examine air samples. To determine the components of a given air sample, most air quality control equipment employ GC in conjunction with FID.

Gas chromatography (GC) is useful in food analysis where food products can be analyzed and measures the quantification of volatile organic of the food products. GC can be used in environmental analysis where identifying the unknown organic compound in hazardous waste and quantification of pollutants in wastewater.

GC Schematic Diagram.

1. Gas supply system
 - To supply carrier gas and gases for the detector. The regulators provide a stable and continuous gas supply. Nitrogen, helium, and hydrogen gases are typically used as the carrier gas to transport the analytes in the GC column.

2. Injection port
 - To provide a place for sample introduction by using a manual syringe technique or an automated injection. The port contains soft septum that provides gas-tight seal; however it can be penetrated by a syringe needle during the sample introduction. The injection port will vaporize the sample in order for it to pass through the column for separation.

3. Oven
 - To control the column’s temperature. The oven allows the interaction of analyte with stationary phase and the boiling point for separation of compounds. The temperature is programmed. Higher temperatures will cause sample to elute faster, thus, may affect resolution.

4. Column
 - The GC column separate the mixture according to their affinity. There are two types of column in the market, packed or capillary. The stationary phase of packed column is coated directly in the column, whereas the stationary phase in the capillary column is coated with the inner wall. The mixture separation is based on the differential partitioning of the components between the mobile and stationary phases. The components that have less affinity to the stationary phase, consequently less interaction, travel faster and elute first and vice versa. 

5. Detector
 -To measure analytes in the gas stream. The Flame Ionization Detector (FID) is one of the most used detectors. FID detects ions formed during combustion of organic compounds in a flame, which generated by hydrogen and air. The collector and polarisation electrodes are used to provide a potential difference. The current produced is measured by a electrometer and amplified into proper voltage before sending to the integrator.

6. Recorder/ Integrator
 -To display and record the data gained. The data is present in a graph and the number of peaks represent the amount of components in the mixture. 

Applications
 -GC/FID is used to analyse air samples for air quality control.
 -GC/MS is used in pharmaceuticals and cosmetic fields.to identify the amount of chemicals in drugs.
 -used for separation of chiral volatile compounds in foods.

Schematic diagram of GC

Application of GC

1.  Carrier gas: Helium, N₂, H, Argon are used as carrier gas to maintain the operating efficiency of the gas chromatograph that is dependent on the maintenance of constant gas flow. 

2.  Sample injection system: it is used to inject the liquid samples by a microsyringe with a needle inserted through a self-scaling, silicon-rubber septum into a heated metal block by a resistance heater. It provides a place for sample introduction, its vaporization and possibly some dilution and splitting. 

3. Oven: oven controls the temperature of column. 

4. Liquid phases: a variety of liquid phase are available limited by their volatility, thermal stability and has the ability to wet the support. 

5. Supports: the structure and surface characteristics of the support materials are important parameters, which determine the efficiency of the support and the degree of separation respectively. 

6.  Detector: detector sense the arrival of the separated components and provide a signal. 

1.     Air-borne pollutants

2.     Performance-enhancing drugs in athlete’s urine samples

3.     Oil spills

4.     Essential oils in perfume preparation

 

1. Gas supply system

A carrier gas that is used to move the solutes through the column. Helium, hydrogen and nitrogen are the most widely used gases. 

2. Injection part

Provide a place for sample introduction, its vaporization & possibly some dilution & splitting. The sample sample is vaporized and transported onto the column by the carrier gas. Sample must be vaporized in injection port in order to pass through column for separation.

3. Oven

Oven is used to control temperature of column. Interaction of analyte with stationary phase & the boiling point for separation of compounds.

4. Detector

Detector provides a quantitative measurement of the components of the mixture as they elute in combination with the carrier gas. 

5. Column

A place where separation occurs. It is through interactions between solutes (individual compounds in the sample, also called analytes) and the stationary phase within the column that separation can occur.

6. Computer / data analysis

Records and shows the result of the analysis.

 

1. Measuring air pollution

2. Quality control in Pharmaceutical Industry

3. Food Analysis

4. Forensic

5. Blood alcohol analysis

1. Gas supply system:
 Carrier gas such as hydrogen gas is used for detector.

2. Injection port:

It provides a place for sample introduction such as vaporization, dilution and splitting. Samples are injected into the injection port by using a manual syringe technique to pass through the column for separation.

3. Oven:

Oven is used to control the temperature of the column. Higher temperature will cause sample to elute faster which will then affect the resolution.

4. Column:

Separation process occur. Outer wall of the column is coated with polyamide material which help to enhance strength and reduce breakage. 

5. Detector:

It detects components of the mixture being eluted off the chromatography column.

6. Recorder and integrators:

Recorded the signals from gas chromatography and chromatogram is generated.

 

Application for gas chromatography:

1. Used to measure air pollution by monitoring the level of harmful pollutants in air.

2. Used in pharmaceutical industry to produce pure products in large quantities and to analyze the trace contaminants.

3. Used in forensics field to determine the cause of the death of the person.

Application of GC:

Analysis of oil spills, analysis of air-borne pollutants, analysis of essential oils

Application of GC
- food analysis
-quality control
-research
-forensic

Flow controller : measure the carries gas flow to make sure the gas flow rate remains constant

Sample injector – manual or automatically controlled injection system which injects constant sample volume each and every time. Liquid sample mixtures are injected with a gas tight syringe and gaseous mixtures are injected with automated injection valves

Injection port- Place for sample introduction, vaporization and possibly some dilution and splitting.

Column –Columns in GC are generally longer and narrower than HPLC columns.These are filled with the stationary phase or the inside wall is coated.Depending on selective adsorption of separated components selective retention takes place.

Detector – Most commonly used detector is the flame Ionisation detector (FID), in which the separated components get ignited in the flame and detector response is dependent on current generated due to compound ionization..Other common detectors are TCD,ECD and FPD.

Data system –Today’s GC systems use a computer to control system parameters such as flow rate, injection sequence and volume, wash cycles, column pressure, detector wavelength, etc and at same time calculate and display the parameters. Chromatograms and results are displayed and printed using user friendly application softwares developed by different manufacturers.

Application of GC
Forensics Analysis, it is used to ascertain the circumstances surrounding a person's death, such as whether they took poison or drank drugs or alcohol in the hours leading up to their death. 

Gas supply system
-supply gas and carry gas for detector (eg. carrier gas and hydrogen gas)

Flow controller
control the carrier gas (volume and pressure) flowing into system. 

Injection port
place where the sample is injected into the system

Column oven
The column enclosed by a column oven, it is responsible for maintaining a constant temperature during isothermal operation.

GC Column
place to separate analytes, filled with the stationary phase. This is done for selective absorbance and retention of the sample components.

Detector
responsible for identification and quantification of components of the sample that eluted from the column

Data system
A software that provides control to operational parameters, the data station calculate and display the results.

1.    Detect impurities in drug formulation

2.    Identification of volatile component

3.    Analysis of pesticides in food industry

Column

This is filled with the stationary phase or its walls are covered with a liquid adsorbent. This is done for selective absorbance and retention of the sample components.

Column Oven
The column is enclosed by a column oven which is responsible for maintaining a constant temperature during isothermal operation. This temperature when temperature programming is needed can be increased in a controlled way for acquiring effective separation of mixture components possessing different volatilities.

Detector

This is employed for the identification and quantification of components. Here, the regions of individual peaks created relate to their concentrations and their retention times are representative of their identity.

Data system
It is a set of dedicated software that provides control over many important operational parameters like injection sequence, wash cycles, over-temperature control, the flow rate of gases, detector wavelength, etc. Simultaneously, the data station calculates and displays the parameters.

3.Application

-Pharmaceutical industry

-Research

-Medical and Forensic
-Environmental monitoring 

-Petroleum refining and petrochemicals
-Edible oils

1. Carrier gas : Carrier gas must be inert (nitrogen, helium, argon, and carbon dioxide).  The carrier gas system contains a molecular sieve to remove water and other impurities. A carrier gas is required to flow through the injector and push the gaseous components of the sample onto the GC column.

 

2. Inject port : Introducing sample to the head of the column. The sample inject to the insturment by manual syringe technique or automated injection. The injector comes in two mode, split or splitless. A calibrated microsyringe is used to deliver a sample volume in the range of a few microliters through a rubber septum and into the vaporization chamber.

 

3. Column : There are two general types of column, packed and capillary (also known as open tubular). The first is a wall-coated open tubular (WCOT) column and the second type is a support-coated open tubular (SCOT) column. The stationary phase is deposited thinly along the column walls of WCOT columns, which are capillary tubes.

The column walls of SCOT columns are initially coated with a thin layer (approximately 30 micrometres thick) of adsorbant solid, such as diatomaceous earth, which is made up of single-celled marine plant skeletons.

 

 

 

 

4. Column Oven : Serves to control the temperature of the column within a few tenths of a degree to conduct precise work. The boiling point of the sample determines the appropriate column temperature. There are two ways to programme the oven: isothermal programming and temperature programming. The temperature of the column is kept constant during the separation in isothermal programming. 

 

5. Detector : In gas chromatography, a variety of detectors can be utilised. Different sorts of selectivity will be produced by different detectors. A non-selective detector responds to all chemicals except the carrier gas, a selective detector to a group of compounds with similar physical or chemical properties, and a particular detector to a particular chemical compound. The detector, which is placed at the end of the column, gives a quantitative measurement of the mixture components as they elute in conjunction with the carrier gas.

 

 

 

Applications :

 

Gas chromatography is a physical separation technique that separates volatile mixtures. It has applications in a variety of sectors, including medicines, cosmetics, and even environmental hazards. GC may be used to examine air samples. To determine the components of a given air sample, most air quality control equipment employ GC in conjunction with FID. Due to the samples must be volatile, Gas chromatography can readily examine human breath, blood, saliva, and other fluids containing substantial volumes of organic volatiles. Knowing how much of each component is present in a sample provides researchers a great edge when researching the impact on human health and the environment.

2. Regulators 

Supply gas at constant pressure

Ensure a constant flow through the column and detector 

A place to inject sample into gas chromatography by automated injection or manual syringe technique. 

Traps water vapor 

Separation of analyte into individual components in the column 

Identify the composition and concentration of separated components by giving electronic signal response

 9. Electrometer

Measure the small signal to a large enough size for ease of gas chromatography 

10. Recorder / Integrator
Recorder record and show the baseline and all peaks obtained

Application of gas chromatography

1. Carrier gas 

 

 

 

 

 

 

i. Flame Ionization Detector (FID)

ii. Electron Capture Detector (ECD)

iii. Thermal Conductivity Detector (TCD)

iv. Flame Photometric Detector (FPD)

 

 

 

1. In forensic analysis

2. Quality control analysis

3. Detection of trace materials and contaminants in pharmaceutical industries

4. Blood alcohol analysis

1. Gas Supply System

a) The gas supply must be in high purity.

b) Supplies the gases to the columns at constant pressure.

2. Regulators

a) Made up from stainless steel instead of polymers to prevent the give off of volatiles by polymers. 

b) Control the pressure and flow of the gases

3. Molecular-Sieve Traps

a) Trap the molecular and remove any moisture and contaminants from incoming gases.

4. Injection Port

a) Provide a place for sample introduction. 

b) The sample will be introduced into the injection port in the form of vaporization in order to pass through column.

5. Oven

a) Control the temperature in the oven.

b) Interaction of analytes with stationary phase & boiling point for separation of compounds. 

6. Column

a) Place for the separation to occurs. 

b) Provides a surface for the components in sample to be interact and slow the samples down for the separation process.

7. Detector

a) Measure the components of the mixture and release electrical signal as output.

8. Electrometer & Integrators

a) Interprets the electrical signal and produce readable chromatograms.

 

1. Determination of food composition and the additives added.

2. Determination of contamination which may present in food, like pesticides. 

3. Determination of drugs residues in the blood and urine.

4. Refining of petroleum products in petroleum industry.

5. Analyze the blood and cloth sample which may help in the investigation of criminals.

- A mobile phase that transfer injected sample to the separation column and separated components to detector. 

- Examples are high purity and chemically inert gas (N, He, H gas)

 

2. Regulator 

-Supply gas at constant pressure

 

3. Molecular sieve trap

s-act as a trap for water vapour

4.Flow controller

-to control the constant flow of carrier gas in volume and pressure that flows through the column and the detector.

5. Sample injection port

-to inject sample into the system through a gas-tight manual syringe or automated injection valves at elevated temperature. 

-usually the samples are injected from range 0.1 to 0.12 ml

6. Oven

- to enclose the column while controlling the temperature of isothermal operation of the column. 

7. Column

- to be filled with stationary phase

- separation process of analytes occur in this place

8. Detector

- to detect, identify, and quantify the components once they eluate from the column.

- gives out electronic signal response to be received by electrometer

 

9. Electrometer

- picks out the electronic signal by detector and transmit them into data

 

10. Recorder 

- To record the data obtained obtained in the form of baseline and peaks obtained over time from the detector after amplification. 

- Integrator can be added to improve the function of a recorder by giving more information on the peaks.

 

 

- analysis of toxic substances of food to ensure food safety in food products

- quality control of medical drug

- identification of component in body test.

 

1.     Gas flow regulator- to control the flow carrier gas

2.     Injector- to vaporize and mix the sample with the carrier gas before the sample enters the head of column

3.     Detector- to give signal response in terms of area counts under a peak and determine the composition and concentration of analyte

4.     Column- contain stationary phase and the passing way of mobile phase that separate the analyte according to their affinity

5.     Oven- to control and maintain the temperature of the column

6.     Data analysis- to record the data of analysis obtained

1.     Analysis of pesticides in soil, water and food

2.     Forensic analysis of blood and urine alcohol levels

1. Carrier gas = The carrier gas must be chemically inert and it also contain a molecular sieve to remove water and other impurities. The commonly used of gases such as nitrogen, helium, argon and carbon dioxide.

2. Sample injection port =  the sample port is the sample where it placed at the head of the column. A calibrated micro-syringe is used to  deliver a sample volume in the range of a few microliters through a rubber septum and into the vaporization chamber. Most of the separations require only a small fraction of the initial sample volume and a sample splitter is used to direct excess sample to waste.

3. Column oven = The thermo-statted oven serves to control the temperature of the column within a few tenths of a degree to conduct precise work. The oven can be operated in two manners:

a)  Isothermal programming: the optimum column temperature for isothermal operation is about the middle point of the boiling range of the sample.

b) Temperature programming: the column temperature is either increased continuously or in steps as the separation progresses.

4. Column : there are two general types of column which it is know as a open    tubular

a) Packed column: contain a finely divided, inert, solid support material which it is commonly based on diamaceous earth that coated with liquid stationary phase.

b) Capillary column: it have an internal diameter of a few tenths of a millimeter. Where it can be one of two types; wall-coated open tubular (WCOT) or support-coated open tubular (SCOT).

5. Detector = it can sense the arrival of the separated components and provide a signal. Where these are either concentration-dependent or mass dependent.

6. Recorder / computer data analysis = the recorder was generally 10mv (full scale) fitted with a fast response pen (1 sec or less). the recorder should be connected with a series of goof quality resistances that connect across the input to attenuate the large signals. Example of GC used for analysis is:

GC analysis is used to calculate the content of a chemical product, for example in assuring the quality of products in the chemical industry; or measuring toxic substances in soil, air or water.

1. Air-borne pollutants

2. Oil spills

3. Essential oil in perfume preparation

 

a)       Carrier gas tank- source to provide the gas that will be used as the mobile phase 

b)      Flow controller- gas flow is controlled with a constant pressure regulatory system

c)       Injection port- sample solution is introduced using a micro-liter syringe

d)      Column- to separates the molecules through interactions between mobile phase and stationary phase

e)      Column oven- to control the temperature for optimal functioning of separation 

f)        Detector- to detect the analyte that has eluted through the column

g)       Data recorder/computing system- record the data and converted into an electrical signal 

 

Application:

-          Air-borne pollution

-          Forensic Science

-          Oil spills

-          Performance-enhancing drugs in athlete’s urine samples

-          Essential oils in perfume preparation

3. Detector - Identify the quantitative measurement of the components of the mixture.

4. Recorder – Collect and record the data of chromatographic separation.

5. Flow controller – Supply gas at constant pressure to the gas chromatography.

6. Column – Allow separation of the analytes according to their affinity.

Applications
1.Forensics-used to determine the circumstances of a person’s death, such as whether they ingested poison, or consumed drugs or alcohol in the hours prior. Scientists take samples of blood and fibers from the crime scene and analyze them using gas chromatography to help investigators piece together the facts. 

2.Food analysis- quantitative and qualitative analysis of food, the analysis of food additives, components of flavor and aroma, and the detection and analysis of contaminants such as environmental pollutants, pesticides, fumigants, and naturally occurring toxins.

3.Measuring air pollution-combats air pollution by monitoring the levels of harmful pollutants in the air so that scientists can visualize where air pollution is more concentrated, and how this changes throughout the day and the year to develop effective preventative methods.