Chromatography

Technique separating compounds

Chromatography is defined in USP <621>, Chromatography, as "a procedure by which solutes are separated by a dynamic differential migration process in a system consisting of two or more phases, one of which moves continuously in a given direction and in which the individual substances exhibit different mobilities by reason of differences in adsorption, partition, solubility, vapor pressure, molecular size, or ionic charge density. The individual substances thus separated can be identified or determined by analytical procedures". There are many types of chromatography methods such as high pressure liquid chromatography (HPLC), gas chromatography, ion exchange chromatography, ion exchange chromatography, and gel permeation chromatography. The selection of the method depends on the analyte. however, HPLC and gas chromatography are the most widely used. In validation of chromatography methods the system suitability, specificity, accuracy, precision, linearity, LOD and LOQ, range, and ruggedness are validated.