Normal- and Reversed-Phase Thin-Layer Chromatography of Amino Acids on Unconventional Supports with Mixed Mobile Phases Containing Dimethyl Sulfoxide

The chromatographic behavior of twenty-four amino acids has been studied on untreated and on triaryl phosphate (TAP)-impregnated adsorbent layers with 1 + 1 dimethyl sulfoxide-1 M HCl as mobile phase. The unconventional adsorbent talc, and alumina, starch, and silica gel GF254 have been used to study the retention behavior of the amino acids. The effect of amino acid pI (isoelectric point) in Ri (RF on unimpregnated layers minus RF on impregnated layers) is discussed. The effect of the molar refractive index (Rm) of the amino acids on their RF values on mixed layers containing talc has also been investigated. The talc-alumina mixture was used to effect several binary separations of amino acids. The mechanism of migration is explained in terms of adsorption by, and the polarity of, the stationary phases used.