Gas chromatography is the most widely used analytical method for quality control as well as identification and quantification of molecules in sample mixtures in many research and industrial laboratories. GC is frequently used in many applications of forensic and environmental as it allows for very small amounts of detection. A large range of samples can be determined as long as the analytes are enough thermally stable and are relatively volatile. Depending on the stationary phase used there are two types of GC, such as gas-liquid chromatography (GLC) and gas-solid chromatography (GSC).
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Principle of gas chromatography (GC):
Gas chromatography is a technique for separating and quantifying vaporized analytes using an inert carrier gas (Nitrogen or Helium). The GC works on the same principles as column permeation chromatography, in which analytes are dissolved in the mobile phase and moved through a porous stationary phase. The basic principle involved in gas chromatography is partitioning, in which the analytes are distributed or partitioned between the two-phase i.e. stationary phase and mobile phase. The analytes are separated based on their affinity, the more affinity will elute slowly while lower affinity toward the stationary phase will elute rapidly from the column.
Gas-liquid chromatography (GLC) is the most regular form of GC, in that a stationary phase is a non-volatile liquid. The stationary phase can be coated on small inert solid particles packed in a coiled metal or glass column. Most analyzes of GC performed in the early years of GC using this kind of packed column. But, in recent years the capillary columns have been widely used since it has more separation efficiency and sensitivity. The carrier gas, sample injection port, column, column oven, and detector, etc. are the components essential to perform the process of GC.
Applications of gas chromatography (GC):
Pharmaceutical applications of GC: The gas chromatography is widely used for the qualitative and quantitative analysis of a sample of formulations and medicinal products in pharmaceutical production.
Analysis of food, flavors, and fragrances: The quality and quantity of fragrances, flavors, and food products are required to be maintained; hence GC is used to analyze them. It is also used to determine the pesticides, and contaminants from foodstuff, vegetables, and fruits.
Applications of GC in the analysis of pesticides: The column of GC provides high resolution, efficiency, and exceptional inertness towards neutral, basic, and acidic compounds, therefore, it is appropriate for the analysis of volatiles and pesticides.
Applications of gas chromatography in academic research: GC-MS is the most powerful technique, it is used for the identification and characterization of molecules, which provide high resolution compared to the HPLC column.
Environmental applications of gas chromatography: GC is the most generally used technique for the identification of organic molecules in environmental samples.
Applications of GC in clinical and forensic purposes: In several fields of forensic science the gas chromatography is used, ranging from the analysis of crime investigations, alcohol, and drug abuse. It is also essential in clinical applications to the analysis of drugs in the blood.
Applications of GC in a variety of industries: Gas chromatography has wide applications in many industries such as the petroleum industry, food industry, beverage industry, pharmaceutical industry,
chemical industry, and gas industry, etc.
Applications of gas liquid chromatography:
A major trend in the field is combining substantial fractionation properties of gas-liquid chromatography with better analytical properties of instruments such as ultraviolet (UV), infrared spectrophotometer (IR), mass (MS), and NMR. In its application for chemical problems, the system must distinguish between two functions operating. The first is as a tool for isolation. In this capacity, it is unmatched, applied to biochemical systems, metal-organic and complex organic.
The second is to offer a means to complete the analysis. Here, the retention time of the compound is working for qualitative detection, while the peak area/height gives quantitative information. In comparison to other approaches, gas-liquid chromatography is a relatively underutilized analytical technology, as it is working with volatile components.
Commonly asked questions on chromatography are as follows.
Which
factors influence the separation of the components in gas chromatography?
The
separation of the components in GC is affected by the vapor pressure, length of
the column, the polarity of analyte versus the polarity of stationary phase on
the column, the temperature of column and oven, the flow rate of carrier gas
and amount of sample injected.
What
is the most commonly used detector in gas chromatography?
There
are many types of detectors are used in gas chromatography such as flame
ionization detector (FID), thermal conductivity detector (TCD), mass
spectrometer (GC/MS), thermal conductivity detector (TCD)and electron capture
detector (ECD), but out of these, the flame ionization detector is most
commonly used detector in gas chromatography.
What
is the major difference between GC-MS and LC-MS?
Both
GC-MS and LC-MS are separation technique used to separate the compounds. The
major difference between GC-MS and LC-MS is that the in GC-MS mobile phase uses
as inert gases such as nitrogen or helium, whereas LC-MS uses a solvent or
mixture of solvents as its mobile phase.
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