The working principle of both is more or less the same, the affinity for the stationary phase of a given molecule will determine its retention time (and as such the separation).

A very crude definition could be:

LCMS (Liquid Chromatography coupled to Mass Spectrometry) is applied mainly for the analysis of thermally unstable molecules in complex samples. (Example, analysis biological fluids)

GCMS (Gas Chromatography coupled to Mass Spectrometry) is applied mainly for the analysis of volatile compounds in complex samples. (example: analysis of gasoline and petroleum products)

When you couple a separation technique to mass spectrometry you can do quantification of a given compound (or compounds) and identification of unknown species. Of course you can do a lot more with these techniques, basically it depends on what do you want to do.

The working principle of both is more or less the same, the affinity for the stationary phase of a given molecule will determine its retention time (and as such the separation).

A very crude definition could be:

LCMS (Liquid Chromatography coupled to Mass Spectrometry) is applied mainly for the analysis of thermally unstable molecules in complex samples. (Example, analysis biological fluids)

GCMS (Gas Chromatography coupled to Mass Spectrometry) is applied mainly for the analysis of volatile compounds in complex samples. (example: analysis of gasoline and petroleum products)

When you couple a separation technique to mass spectrometry you can do quantification of a given compound (or compounds) and identification of unknown species. Of course you can do a lot more with these techniques, basically it depends on what do you want to do.

In LCMS,the analyte must be soluble in the mobile phase that is used as mobile phase or carrier solvent, while in GCMS , gas phase is used to elute the analyse. This means that the analyte used for LCMS must be soluble in the mobile phase, while analyte for GCMS must be volatile and does not decompose upon heating. The detection principles are almost similar, using the mass fragments that resulted from ionisation of the molecules. Basically, for volatile compounds, GCMS is very useful, while for polar compounds, LCMS is more useful.

LC-MS -MS works on soft ionization technique where as GC-MS works on hard ionization technique. These is a basic differences between two. LC-MS-MS is useful for non volatile compounds , vitamins, amino acids, protein and pep tides having molecular weight in Kilo Dalton. It is very much useful for studies purity and impurity profiles in drugs. So these tool has wide application in R & D in pharmaceutical industries.

GC-MS is useful for identification volatile compounds having molecular weight less than 1200 amu. It useful in petro chemical , pesticides industries and in field of perfumery .

Answer in parts....

LC is applied mostly in the life sciences and related fields of chemistry. Unlike gas chromatography, which is unsuitable for nonvolatile and thermally fragile molecules, LC can safely separate a very wide range of organic compounds, from small-molecule drug metabolites to peptides, f-PUFA and its metabolites (PGE, EPA, HETEs, PGDs etc.) and proteins. Mass spectrometers also generate three dimensional data. In addition to signal strength, they generate mass spectral data that can provide valuable information about the molecular weight, structure, identity, quantity, and purity of a sample. Mass spectral data add specificity that increases confidence in the results of both qualitative and quantitative analyses. So when you couple the both technique, LCMS, you'll be sure of high specificity, sensitivity, high through put and devoid of several derivatization and complex sample preparation required by the GCMS. GCMS is better applied in the petrochemical and allied chemical industries (pesticides etc.)

Broadly, the working principle for two of them is same; adsorption of the material of interest on the stationary phase and the time it takes of it to be eluted. But them more strikingly, GC-MS analysis is solely concern with volatile materials, as applied in petroleum, perfumery industries and all that, while LC-MS analysis focuses on thermally unstable and nonvolatile molecules. LC-MS is quite useful in analysis of vitamins, amino acid, drugs etc

GCMS or LCMS is a dual system constituting a separation system and detection system. In GCMS the separation system is Gas chromatograph which is couples with the detection system i.e. mass spectrometer. The same is applicable to LCMS. The basic difference between the two is in GC the mobile phase is gas which acts as carrier gas and in LC the mobile phase is liquid. The detection system is same in both cases.

Generally, Chromatography is an analytical technique used for the separation of complex chemical mixtures into individual components. The sample is carried through a separating column by a mobile phase where the mixture is divided into unique bands based on the amount of interaction between the individual analytes and the stationary phase in the column. As these bands leave the column, their identities and quantities are determined by a detector. When either LC or GC is coupled to MS, then we have LC-MS or GC-MS.

In LCMS the mobile phase is below its critical temperature and above its critical pressure, it acts as a liquid, so the technique is liquid chromatography and when the mobile phase is above its critical temperature and below its critical pressure, it acts as a gas so the technique is gas chromatography (GC).

GCMS is inapplicable for nonvolatile or thermally unstable compounds, unlike LCMS

LC/MS systems facilitate the analysis

of samples that traditionally have been

difficult to analyze. Despite the power and

usefulness of gas chromatography/mass

spectrometry (GC/MS), many compounds

are impossible to analyze with GC/MS.

GCMS is mostly preferred to LCMS in terms of cost and operation. However, it is very well noted that there ionisation mechanisms are way different, including there carrier medium, GCMS exhibit substantial ion fragmentation as compared to LCMS. 

The two are different separating techniques that constituting a separation system and detection system. In LCMS, Liquid is the mobile phase while in GCMS, gas is the mobile phase. But I will suggest if you can try both techniques because GCMS will give you a clear representation of some volatile compound present while LCMS will also give you some information about some non-volatile compounds.

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