J. Planar Chromatogr. 21, 125-128 (2008). TLC of a racemic mixture of diastereomeric salts formed by pipecoloxylidides (pipecoloxylidide, mepivacaine, N-ethylpipecoloxylidide, ropivacaine, bupivacaine) with O,O’-dibenzoyl-2R,3R-tartaric acid on silica gel with 1-butanol - glacial acetic acid - water 12:3:5 after chamber saturation for 2 h at 25 °C. TLC was also performed using 2-propanol, ethanol, and methanol instead of 1-butanol. Detection by spraying with 1 N potassium permanganate solution and Dragendorff reagent. Evaluation under UV light.

Acta Chromatographica 21(1), (2009) . This study focused on the attempt to suppress the spontaneous oscillatory in-vitro chiral conversion of a-substituted propionic acids using, as example, L-lactic acid dissolved in water in the presence of copper(II) cations to check whether the coordinate covalent bonds between copper(II) and L-lactic acid ligands prevented the latter species from oscillatory chiral conversion. Aqueous solutions of copper(II) acetate and lactic acid in the molar ratios 1:1, 1:2, and 1:3 were stored and the possible chiral conversion of L-lactic acid was monitored by TLC, polarimetry, and circular dichroism spectroscopy. It was found that chelating of copper(II)cations with L-lactic acid did not result in suppression of the spontaneous oscillatory in-vitro chiral conversion of the acid from the TLC data. Different molar proportions of copper(II) cation and L-lactic acid had somewhat different effects on the dynamics of conversion, in contrast, when L-lactic acid is dissolved in water in the presence of copper(II)cations almost no chiral conversion is observed from polarimetric and circular dichroism studies. It was therefore concluded that chelating of copper(II) cations with L-lactic acid stabilizes the chiral structure of the acid in solution. The structure-stabilizing effect of copper(II) cations is weakened by the TLC system due to the interaction of the copper(II)-L-lactic acid complex with the silica gel.

J. Chromatogr. Sci. 54 (5), 842-846 (2016). Development of a new chromatographic method for direct enantioresolution of (RS)-baclofen by ligand-exchange TLC, adopting two different approaches: (A) on plates prepared by mixing the ligand exchange reagents (LER) with silica gel slurry, development with different achiral solvents or solvents without chiral additive; (B) on silica gel without chiral selector and the LER consisting of Cu(II)–L-amino acid complex as chiral mobile phase additive. Preparation of LERs by using Cu(II) acetate and four L-amino acids (L-tryptophan, L-histidine, L-proline and L-phenylalanine). Detection by exposure to iodine vapor. Study of the effect of temperature and the mole ratio of Cu(II)-to-amino acid on enantioresolution. L-tryptophan proved to be a good ligand using a common mobile phase in each case.

Chromatographia 27, 301-305 (1989). Investigation of the applicability of chiral reagent, S(-)-N-1-(2-naphtylsuphonyl)-2-pyrrolidinecaronylchloride, to the resolution of amino acid enatiomers. TLC of diastereomeric amino acid derivatives on silica with chloroform - methanol 98:2. Detection under UV 254 nm. Also HPLC. Complete resolution was obtained for the enantiomers of all amino acids examined except cysteine, cystine and histidine.

Chromatographia 32, 278-284 (1991). Presentation of a new chiral ligand exchange selector for hydrophobic stationary phase modification from selective alkylation of L-histidine at the pyrrolic nitrogen atom in its imidazolic ring. Test of its performance on reverse-phase HPTLC plates treated with copper acetate. Separation of amino acids with various aqueous solvents. Comparison of the retention data with thermodynamic complex formation parameters.

Adsorption of tryptophan and derivatives from CuSO4-containing eluents. J. Chromatogr. 645, 185-188 (1993). Discussion of the influence of the presence of CuSO4 on the chiral discrimination of cellulose for the compounds. Comparison of the results with those from a previously published paper.

J. Chromatogr. 685, 360-364 (1994). TLC of amino acid racemates on the title plates with 1) 2-propanol - water 7:3, 2) phenol - water 4:1, 3) butanol - acetic acid - water 3:1:1. Detection by spraying with 0.1% ethanolic ninhydrin solution and heating for 5 minutes at 90 °C. Discussion of the enantiomeric separation mechanism.

J. Planar Chromatogr. 11, 346-349 (1998). TLC of the enantiomers of several unusual aromatic amino acids (phenylalanine, tyrosine, histidine, and tryptophan analogs, and analogs containing tetralin or 1,2,3,4-tetrahydroisoquinoline skeletons) synthesized in racemic or homochiral form on chiral plate with acetonitrile - methanol - water 4:1:1; 4:1:2 or acetonitrile - methanol - water - diisopropylethylamine 40:10:20: 1. Visualization with ninhydrin.