Normal-phase chromatography can sometimes provide satisfactory resolution of hydrophilic and even ionic samples. Very hydrophilic samples such as carbohydrates may be too weakly retained in RPLC systems to allow their separation. They are well retained in normal-phase systems, but usually are not sufficiently soluble in the non-aqueous mobile phases. In normal-phase chromatography, the stationary phase is polar and the mobile phase is nonpolar