V. Coas

Reversed phase planar chromatography of dansyl DL amino acids with bovine serum albumin in the mobile phase

SummaryThe chromatographic behavior of twelve dansyl DL amino acids, one D isomer and eleven L isomers on RP18W/UV254, RP18W/F254s, and Sil C18−50 UV254 plates developed with aqueous—organic solutions containing bovine serum albumin (BSA) as chiral complexing agent has been extensively investigated. Enantiomeric resolution is highly dependent on mobile phase pH and ionic strength, and on the concentration of both BSA and organic modifier. All the racemates have been resolved within a development time of 1 h 30 min. The selectivity factors (α) for the dansyl amino acids have been compared with those from planar chromatography for the corresponding DNP, DNPy, and Fmoc amino acids, and with those of the same dansyl derivatives on a column prepared from BSA bound to silica gel.

Thin-layer chromatographic and electrophoretic behaviour of primary aromatic amines on weak ion exchangers

Abstract The authors have studied extensively the thin-layer chromatographic and electrophoretic behaviour of primary aromatic amines on weak ion exchangers such as alginic acid and carboxymethylcellulose. The eluents were solutions of organic and inorganic acids, water, buffer solutions and aqueous organic solvents. The R F values were correlated with the acidity and basicity of many amines.

Ion-change thin-layer chromatographic separation of amino acids on alginic acid

Abstract Alginic acid was tested as an adsorbent in the ion-exchange chromatography of 31 amino acids on thin layers, the eluents being hydrochloric acid, acetic acid, water, potassium nitrate solutions and aqueous organic solvents. The behaviour of the amino acids on alginic acid was compared with their behaviour on carboxymethylcellulose. An ion-exchange mechanism operates in the case of basic amino acids. As regards the neutral amino acids, their affinity for alginic acid seems to be influenced by steric hindrance.

Separation and identification of water-soluble food dyes by ion-exchange and soap thin-layer chromatography

Eighteen water-soluble food dyes have been studied by chromatography on thin layers of anion-exchange (AG 1-X4, DEAE-cellulose, PAB-cellulose and chitosan) and cation-exchange (Dowex 50-X4, Rexyn 102 and humic acid) materials; layers of silanised silica gel impregnated with cationic or anionic detergent were also used. Fourteen of the dyes were separated, but the two orange and the two black dyes were not. Some applications of the techniques to commercial products are reported.

Chromatographic and electrophoretic behavior of purines and pyrimidines on layers of weak and strong cation exchangers.

Abstract The chromatographic behaviour of seven purines, fourteen pyrimidines and three nucleosides on thin layers of alginic acid, sodium carboxymethylcellulose and Dowex 50-X4 (H+ and Na+ was investigated. The eluents used were water, buffer solutions and mineral acid solutions. The possible separations are discussed. The retention mechanisms of these compounds, of eight pyridines and of eight primary aromatic amines are correlated and explained, on both cellulose- and polystyrene-based ion exchangers The applicability of the relation: −n log aH+ = RM + constant is discussed when using eluents with high protonic activity. Finally, as regards the retention of the bases by Dowex 50-X4 (H+), the influence of interactions between the sulfonic groups of the resin and the polar groups of the compounds is discussed.

Chromatographic and eletrocphoretic behaviour of primary mono- and diamines on layers of weak and strong ion exchangers

Abstract The chromatographic behaviour of thirty primary aliphatic amines on Dowex 50 X 4 (NA + and H + ), sodium carboxymethylcellulose and Rexyn 102 (Na + ) thin layers has been studied using HCl, buffer and salt solutions as eluents. Some interesting separations are reported; the affinity sequencies on these exchangers are compared with those observed in column chromatography. The retention mechanism has been investigated by applying the R M — log a HCl relationship and the activity coefficients in the “mobile phase” are calculated. The factors underlying the ion-exchange selectivity of these amines are discussed.

Chromatographic and electrophoretic behaviour of primary aromatic amines on anion-exchange thin layers

Abstract The use of polystyrene-based anion exchangers with aqueous eluents for the separation of primary aromatic amines has been investigated, and extended with satisfactory results to microcrystalline cellulose, cellulose-based anion-exchangers and sodium CM-cellulose layers. Interesting separations of the amines have also been effected electrophoretically on AG 1-X4 layers. The use of water-organic solvent mixtures on polystyrene-based cation exchangers is discussed.

Separation of primary aromatic amines on alginic acid and carboxymethylcellulose columns

Abstract The chromatographic behavior of primary aromatic amines in columns of algina acid and carboxymerthylcellulose was investigated extensively. Aqueous solutions of mineral acids and organic acids, water and aqueous—organic solvents were used as eluents. The relation between the data obtained on a thin layer and those obtained in a column was examined.

Chromatographic behaviour of aromatic amino acids on thin layers of anion and cation exchangers

Abstract The chromatographic behaviour of 29 aromatic amino acids (18 sulphonic, 9 carboxylic and 2 arsonic) on both cellulose and polystyrene-based anion and cation exchangers was studied. The influence of the protonation of the amino group on the selectivity of the polystyrene-based anion and cation exchangers towards such compounds was investigated, and the influence of the addition of ethanol to the aqueous eluent on the cation exchanger in the acid form was also studied.

The behaviour of cation-exchange thin layers with alkaline and neutral salt solution as eluents

Abstract The behaviour of weak and strong ion exchangers in the sodium salt form is studied using neutral solutions of uni- and divalent ions and alkaline solutions of univalent ions as eluents. The influence of various parameters (rate of exchange reaction, diffusion rate, swelling capacity, etc.) on the chromatographic behaviour of the ions has been investigated. The conditions for the determination of ionic charge and the selectivity coefficients of the exchangers for some univalent and divalent ions are given.