Applications of the Gas Chromatography

 

Applications of Gas chromatograph

 

Applications of gas chromatography are as following:

1.Qualitative analysis:

   By comparing the retention time or volume of the sample to sample to the standard/ by collecting the individual components as they emerge from the chromatography and identifying these compounds by other methods like UV, IR, NMR.

2.Quantitative analysis:

                                       Area under a single component elution peak is proportional to the quantity of the detected component /  response factor of the detectors.

a.  Direct comparison method:

A_(sample) / A_{(std) =}αC_(sample) /C_(Std)

Where,α is the response factor determined for every pure compound under given conditions.

b.  Calibration curve:

A graph is plotted  by taking peak areas on y-axis and concentration of standard compounds on x-axis. Concentration of the unknown sample is then determined by putting the value of its peak area on same graph.

C.  Internal standard method:

A known concentration of internal standard, which has similar retention characteristics that of sample is added to both reference standard and test sample.

3.                       Pharmaceutical:

Quality control and the analysis of the drug products like antibiotics (penicillin), antivirals (amantadine), general anesthetics (chloroform, ether), sedatives / hypnotics a

Assay of drugs-purity of compound can be determine for drugs like;

·      Atropine sulphate

·      Clone oil

·      Stearic acid

·      In determining the levels of metabolitics in body fluids like plasma, serum, urine etc.

4.                       Food and beverages applications:

 

·      Food and beverages contain numerous aromatic compounds, some naturally present in the raw material and some forming during processing.

·      GC is extensively used for the analysis of these compounds which include esters, fatty acids, alcohols, aldehydes, terpenes etc.

·      Analysis of food is concerned with the assay of lipids, proteins, carbohydrates, preservatives, flavours, colorants, vitamins, steroids, drugs, and pesticides residues.

·      Most of the components are non-volatile (thus the use of HPLC) but with modification, GC can be effectively used.

·      It is also used to detect and measure contaminants from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies For example; pesticides.

5.                       Chemical analysis:

The GC analysis of xylene isomers, there the xylene isomers are precursors to many chemicals;

·      o-xylene is a precursor for phthalic anhydride

·      m-xylene is a precursor for isophthalic acid

·      p-xylene is a precursor for terephthalic acid and dimethyl terephthalate.

Thecresol (methyl phenol) isomers are also precursors to many chemicals. This the chromatogram of a mix of aromatic and methyl phenol compounds was generated using on SLB-IL60 ionic liquid column. Its interaction mechanisms allow the separation of all three xylene isomers, and all three cresol isomers.

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