TLC UV GC HPLC

1. TLC (Thin Layer Chromatography)
Working Principle: TLC is a technique that involves coating a thin layer of stationary phase (such as silica gel or alumina) on a flat surface (like a glass plate or aluminum sheet) and using a mobile phase (solvent or solvent mixture) for separation. As the mobile phase migrates across the plate, components of the sample separate along the surface based on their differing affinities for the stationary phase.

2. UV (Ultraviolet Spectrophotometry)
Working Principle: Ultraviolet spectrophotometry is a technique for qualitative and quantitative analysis by measuring the intensity of light absorption by a sample in the ultraviolet wavelength range (200–400 nm). When ultraviolet light is absorbed by the sample, its absorbance exhibits a linear relationship with concentration. According to the Beer-Lambert Law, the concentration of the sample can be calculated.

3. GC (Gas Chromatography)
Working Principle: The basis of gas chromatography is partition, where components of a sample distribute between two phases: the stationary phase and the mobile phase. Compounds with greater affinity for the stationary phase spend more time in the column, thus eluting later and exhibiting longer retention times (Rt) compared to compounds with higher affinity for the mobile phase. The affinity for the stationary phase is primarily driven by intermolecular interactions, and the polarity of the stationary phase can be selected to maximize these interactions, thereby achieving separation.

4. HPLC (High-Performance Liquid Chromatography)
Working Principle: HPLC, commonly known as High-Performance Liquid Chromatography, is an analytical technique used to separate, identify, or quantify each component in a mixture. It applies the fundamental principles of column chromatography to separate mixtures, followed by identification and quantification via spectrometry. In the 1960s, column chromatography (LC) using low-pressure glass columns evolved into chromatography using high-pressure metal columns (HPLC). Thus, HPLC is essentially a highly advanced form of column liquid chromatography. Instead of solvents dripping through the column by gravity, they are forced through the column under high pressure, up to 400 atmospheres.