How do your read gas chromatography data?

Answer 1

u have to see the ink that comes and see which 2 colours are same and next to each itherr

That is for paper chromatography!

In gas chromatography you determine the concentration of the compound of interest in the sample by determining the area under the peak (AUC). The bigger the peak the higher the concentration. You compare this value to the standard curve that should be run at the same time, to determine the quantitative concentration value. The order of the peaks in the chromatograph tells you which compounds exited first and which where "retained" longer. Retention time is specific for a given compound under the conditions of the GC and can be used to identify your compound of interest.

Answer 2

Gas chromatography (GC) does not necessarily work in a specific way.

Gas chromatography (GC), is used in analytical chemistry to

• separate and analyze compounds that can be vaporized without decomposition
• test the purity of a particular substance
• separate the different components of a mixture
• determine the relative amounts of components
• identify some compounds
• prepare pure compounds from a mixture.

There are many types of chromatography, however, GC takes into consideration affinity, volatility, ion exchange, size exclusion and molecular weight between a sample and a stationary phase.

For example, two types of chromatographic columns are discussed here: (1) packed columns and (2) capillary columns.

Packed columns consist of a column with many solid particles that are covalently covered with a viscous liquid, like Carbowax 20M. The liquid needs to have an extremely high boiling point in order to be effective in a column due to the fact that when the sample is injected to the column, the equipment must be 50*C over the less volatile component of the sample. Carbowax is a polar liquid thus in a column that contains Carbowax, polar substances will be retained in the stationary phase longer than non polar substances due to the higher affinity between polar compounds, the 'like dissolves like' principle.

In essence, a sample plug is injected into a column. The sample is pushed by an inert carrier gas like Helium. The sample is then separated in the column by the stationary phase and sample interactions. (carbowax and sample). After passing through the column, the sample reaches a detector which can be any type of detector, commonly a thermal conductivity detector which measures the thermal conductivity of the carries gas (helium is the most thermally conductive gas, thus when sample reaches the detector, conductivity decreases). This generates an electrical signal that transforms into a chromatogram.

Capillary columns are much more effective than packed columns. These use sample much smaller in volume (microsyringes are used). These capillary columns do not have solid particles inside thus automatically reduce the random error produced by solid particles in packed columns. Van Deemter states that plate height is equal to the multiple paths taken by a sample plus a molar absorptivity coefficient over the flow rate plus the mass transfer coefficient times the flow rate. Capillary columns have a multiple path created by the sample so small it is 'depreciable'.