 Retention increases as the amount of the polar solvent (water) in the mobile phase increases.Normal phase chromatography, an adsorptive mechanism, is used for the analysis of solutes readily soluble in organic solvents, based on their polar differences such as amines, acids, metal complexes, etc.. Reversed-phase chromatography, a partition mechanism, is typically used for separations by non-polar differences.The "hydride surface" distinguishes the support material from other silica materials; most silica materials used for chromatography have a surface composed primarily of silanols (-Si-OH).