Chromatogram

Definition - What does Chromatogram mean?

A chromatogram is a two-dimensional plot with the y-axis depicting detector response for concentration and the x-axis representing time. The height of the peak in the detector response depends on concentration of the particular component.

Gas chromatography is gaining importance in oil analysis labs for determining the concentration of contaminants present in the oil. It can be divided into two categories: Gas-liquid chromatography and gas-solid chromatography.

Chromatography is used to separate mixture using laboratory technique. The mixture is dissolved in fluid called the mobile phase that carries it through a structure holding another material called the stationary phase.

Trenchlesspedia explains Chromatogram

Gas-liquid chromatography depicts the interaction between the gaseous sample/mobile phase and a standard liquid/stationary phase which is a polar or nonpolar liquid. The interaction results in the separation of different molecular constituents. The apparatus consists of an inert gas carrier such as helium or nitrogen, a gas chromatography column, an oven with temperature control and a detector.

The molecules in the sample partition between the gas and liquid phase. Molecules with greater solubility in the liquid phase take a longer time to elute and are measured at longer intervals. The commonly employed method to detect eluting molecules is flame ionization. In flame ionization, the eluting sample is passed through a hydrogen gas flame, causing any molecules present to be ionized resulting an increase in ion flux.

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