J. Planar Chromatogr. 26, 26-30 (2013). Four new spray reagents for the detection of amino acids were introduced: (1) 0.25 % solution of benzoic acid in ethanol, (2) 0.1 % solution of p-fluorobenzoic acid in ethanol, (3) 0.1% solution of p-chlorobenzoic acid in ethanol and (4) 0.05 % solution of p-iodobenzoic acid in ethanol. Depending on the different amino acids tested the LOD on silica gel was in the range of 0.1-1.0 µg for all four reagents. For example for cysteine the LOD was 0.1 µg with reagents (1), (3), and (4), and 0.2 µg with reagent (2).

obshchej chim. 53, 216-221 (1983). (Russian). (Use of pivaloyl chloride for the synthesis of peptides, containing nonsubstituted oxiamino acids). TLC of peptides on silica with a) chloroform - acetic acid - water 85:5:10; 70:15:15; b) butanol - acetic acid - water 13:2:5, c) butanol - acetic acid - pyridine - water 5:1:5:4. Detection with ninhydrin solution.

J. Liquid Chromatogr. 7, 1359-1365 (1984). TLC of 20 essential amino acids on silica, impregnated with copper sulfate or mixed layers silica-polyamide 5:1 with methanol - BuOAC - acetic acid - pyridine 20:20:10:5. Detection with 0.1 % ninhydrin in acetone and heating at 60 °C for 60 minutes.

J. Planar Chromatogr. 3, 247-250 (1990). TLC of tryptophan on cellulose with 1-butanol - acetic acid - water 4:1:5. Detection by overpressure derivatization (OPD), which is carried out by pressing an absorbent polymeric pad (prewetted with derivatization reagent) on the TLC plate. Relative standard deviations obtained showed that OPD was more reproducible than spraying. Quantification by densitometry (absorbance at 420 and 288 nm after derivatization).

J. Agric. Food Chem. 46, 277-280 (1998). Detection of Amadori compounds in reaction mixtures (carbohydrates and amino acids , e.g. arginine, proline, fructosyl-y-aminobutyric acid) by TLC on cellulose with 1-butanol - pyridine - water 2:3:1. Detection by spraying with 0.5% 2,3,5-triphenyl-2H-tetrazolium chloride in 0.5 mol/L sodium hydroxide solution.

J. Liq. Chromatogr. Relat. Technol. 30, 2891-2902 (2007). HPTLC of L-glutamate and L-aspartate on silica gel by double elution with n-butanol - acetic acid - water 13:3:5 in a chamber saturated for 3 h. Detection by spraying with 0.2 % ninhydrin solution in acetone. Quantitative determination by absorbance measurement at 486 nm.

J. Planar Chromatogr. 24, 6-9 (2011). Two-dimensional separation of eight amino acids (arginine, phenylalanine, histidine, glutamic acid, leucine, lysine, threonin, and tryptophan) by HPTLC in the first dimension and pressurized planar electrochromatography in the second, orthogonal direction. HPTLC on RP-18, prewashed by dipping into methanol for 1 min, with acetonitrile - buffer solution. Buffer solutions of pH 3.2-7.0 were prepared by mixing 0.1 M citric acid with 0.2 M disodium hydrogen phosphate. Chromatogram development was performed with 10 % acetonitrile in buffer (pH 3.2) in a horizontal chamber after saturation for 15 min. Then the HPTLC plate was prewetted with mobile phase, inserted into the PPEC chamber and separation was performed for 21 min at a polarization voltage of 2.5 kV. Detection by spraying with ninhydrin reagent followed by heating under a hot air stream. Combination of HPTLC and PPEC in a two-dimensional process leads to substantial enhancement of amino acid separation.

J. Planar Chromatogr. 28, 144-151 (2015). TLC of L-cysteine on cellulose phase with 2-butanol - pyridine - glacial acetic acid - water 5:10:3:12. Just before development an equimolar amount of (1) manganese(II) acetate or (2) zinc(II) nitrate was added to the sample solutions. Detection in reflectance mode at 485 nm, concentration of L-cysteine and DL-cysteine in 70 % aqueous acetonitrile was 0.7 mg/mL. Developing distance was 7 cm, development time ca. 3 h. Derivatization by spraying with 0.5 % ninhydrin solution in 2-propanol, followed by heating for 5 min at 110 °C. The experiments demonstrate the spontaneous chiral conversion and spontaneous peptidization of L-cysteine, and the enantioseparation of L-cys and D-cys enantiomers is facilitated by chelating the transition metal cation (e.g. Mn(II)) with the cys ligands.