Chemical Analysis: Chromatography

Chromatography is a laboratory technique used to separate mixtures into their individual components.
It comprises a mobile phase, which could be a liquid or a gas, and a stationary phase, which is typically a solid.
It exploits physiological properties like different absorption rates and solubility levels of various substances.

Chromatography works on the principles of distribution and adsorption.
Distribution plays on the substance’s likeness for the mobile and stationary phases. Hence substances that favour the mobile phase move quicker.
The principle of adsorption means substances with higher affinity for the stationary phase will take longer to move.

Some main types of chromatography include Paper Chromatography, Thin-Layer Chromatography (TLC), Gas Chromatography, and High-Performance Liquid Chromatography (HPLC).
Paper Chromatography, simple and cost-effective, uses paper as the stationary phase.
Thin-Layer Chromatography (TLC) uses a thin layer of a substance like silica gel on a plastic or glass plate as the stationary phase.
Gas Chromatography is where the mobile phase is a gas like helium or nitrogen, and it separates volatile liquid samples or gases.
High-Performance Liquid Chromatography (HPLC) uses high pressure to push a liquid sample through a column filled with a solid adsorbent material.

Chromatography is suitable for separating both organic and inorganic compounds.
It finds use in different areas such as food and beverage industry for quality control, in medicine for drug testing and in pollution monitoring.

A vital factor to consider in chromatography is the retention factor (Rf), which is the ratio of how far the component travels compared to how far the solvent travels.
Changing the polarity of the solvent can manipulate this value, thus enabling separation and identification of different substances.

The separated components appear as spots in paper and TLC, or peaks in Gas chromatogram.
The distance travelled by the spots or the retention time for the peaks allows for comparison with known standards, hence aiding in identification of the substances.
Comparing the area under each peak allows for quantification of the substance’s quantity in a mixture.

Remember, careful observation, comparisons with known standards, and proper calculations are key to accurate and conclusive chromatographic analysis.