Explain the principles behind chromatography as a separation technique and provide examples of its applications in analytical chemistry.

Chromatography is a versatile separation technique based on differential partitioning between a mobile phase and a stationary phase. It involves the passage of a sample mixture through a chromatographic column or stationary phase, where individual components interact differently with the stationary phase and elute at different rates, resulting in separation. Examples of chromatographic methods include gas chromatography (GC), liquid chromatography (LC), and high-performance liquid chromatography (HPLC). Applications of chromatography in analytical chemistry include quantitative analysis of drugs, environmental pollutants, food additives, and biomolecules like proteins and nucleic acids.