Different combinations of organic and inorganic solvents may be used depending on the analyte. Thin layer chromatography TLC Calculating retention factors for TLC. Hplc High Performance Liquid Chromatography Gas Chromatography Liquid High Performance Gas Chromatography GC or GLC is a commonly used analytic technique in many research and industrial laboratories for quality control as well as identification and quantitation of compounds in a mixture. . 11 This is a liquid chromatographytandem mass spectrometry LCMSMS method for the determination of selected perfluorinated alkyl acids PFAAs in drinking water. In planar chromatography in particular the retardation factor R F is defined as the ratio of the distance traveled by the center of a spot to the distance traveled by the solvent front. Chromatographysolid or liquid as a mobile phase a liquid or gas passes over the stationary phase. Chromatography usually is divided into