Gas chromatography-mass spectrometry

BY

Pintu Choudhary

Master of Technology

( Food Science and Technology)

Indian Institute of Crop Processing Technology

Ministry of Food Processing Industries

Government of India

Thanjavur - 613005

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Gas chromatography-mass

spectrometry

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Gas chromatography-mass

spectrometry

• Gas chromatography–mass spectrometry (GCMS) is an

analytical method that combines the features of Gas

chromatography and mass spectrometry to identify

different substances within a test sample

• Applications of GCMS include drug detection, fire

investigation, environmental analysis, explosives

investigation, and identification of unknown samples.

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Gas chromatography

• Gas chromatography is a column chromatography technique, in

which the mobile phase is gas and the stationary phase is either an

immobilized liquid or a solid packed in a closed tube.

• GC is used to separate thermally stable volatile components of a

mixture

• Gas chromatography, specifically gas–liquid chromatography,

involves vaporizing a sample and injecting it onto the head of the

column

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Mass Spectrometry

• Separation of molecular & atomic species

according to their mass to charge ratio.

• Used in the analysis of samples from elemental

to large proteins and polymers.

• Both qualitative and quantitative analysis

possible.

• Can be used in conjunction with gc, lc .

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Sample preparation

1. Introduction of (purified) sample extract onto the GC

column,

2. separation of its components on an analytical column and

3. detection of target analytes by currently the most

commonly used device—mass spectrometric (MS)

detector.

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Sample preparation

Sample

Size reduction

Refrigeration

Inactivation of enzyme

Heat treatmentDrying

Cleaning

Microbial inactivation

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Example of sample preparation Fatty acids in food

Transesterification

Formation of ester to improve gas chromatographic properties

Hydrolyze the fatty acids

Isolation

Extraction of lipids(e.g. solvent extraction )

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Process of analysis

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Process of analysis

• These materials for GC analysis may be isolated by headspace analysis

(static or dynamic), distillation, preparative chromatography (e.g., solid-

phase extraction, column chromatography on silica gel), simple solvent

extraction, or some combination of these basic methods.

• The procedure used will depend on the food matrix as well as the

compounds to be analyzed

• The primary considerations are to isolate the compounds of interest from

nonvolatile food constituents (e.g., carbohydrates, proteins, vitamins) or

those that would interfere with GC (e.g., lipids).

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Principle of detector

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Parts of GC

The major parts of a GC are the gas supply system,

• injection port,

• oven,

• column,

• detector,

• electronics, and

• recorder/data handling system

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System of GCMS

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Advantages of GC–MS over traditional

approaches

It include :-

• Simultaneous quantification and confirmation of

target analytes

• Detection and identification of non-target sample

components

• Possibility to spectrometric-ally resolve co-

eluting peaks

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Application of GCMS

• Residual volatiles in packaging materials

• Separation of stereoisomers

• Headspace analysis of ethylene oxide in spices

• Aroma analysis of food

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Application of GCMS

• GC has been used for the determination of fatty acids, triglycerides,

cholesterol and other sterols, gases, solvent analysis, water, alcohols,

and simple sugars, as well as oligosaccharides, amino acids and

peptides, vitamins, pesticides, herbicides, food additives,

antioxidants, nitrosamines, polychlorinated biphenyls (PCBs),

drugs, flavor compounds, and many more

• GC is ideally suited to the analysis of thermally stable volatile

substances.

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Application

• Pesticides

• Polychlorinated biphenyls

(PCBs)

• Polychlorinated dibenzo-p-

dioxins and dibenzofurans

(PCDDs/PCDFs), dioxine-like

polychlorinated biphenyls, and

dioxine-like PCBs

• Polybrominated diphenyl ethers

(PBDEs)

• Polycyclic aromatic

hydrocarbons (PAHs)

• Mycotoxins

• Veterinary drug residues

• Acrylamide

• Chloropropanols

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References

• Kitson, F. G., Larsen, B. S., McEwen, C. N.: 1996,

Gas chromatography and mass spectrometry: a

practical guide, Academic Press, San Diego.

• Chester TL, Pinkston JD, Raynie DE (1996)

Supercritique fluid chromatography and extraction

(fundamental review). Anal Chem 68:487R–514R

• Nielsen S (2010) ,Food analysis,Sringer,USA.3/15/2015 18