J. Liq. Chromatogr. Relat. Technol. 43, 580-588 (2020). Retardation factor (hRF) of 42 amino acids in two different eluents (acetonitrile - sodium azide and 1,2 dioxane-sodium azide solutions) were predicted by different quantitative structure-retention relationship (QSRR) methods. The method analyzed the effect of sum of geometrical distances between N and O in separation of amino acids in RP-TLC.

J. Chromatogr. 245, 297-308 (1982). Investigation of the chromatographic characteristics of amino acids, peptides, amino sugars, aliphatic mono- and polyamines on precoated plates of RP-18 and SIL C18-50 untreated or impregnated with dodecylbenzenesulfonic acid on layers of ammonium and tetramethylammonium tungstophosphate using water - alcohol mixtures at different pH and ionic strengths or aqueous solutions of nitric acid, ammonium nitrate and tetramethylammonium bromide as eluents.

Acta Physica et Chemica 29, 121-128 (1983). TLC of dansyl tryptophan on silica with ethyl acetate - acetic acid - methanol 20:1:1. Photometry after elution at 335 nm.

Part CLXXXII. Vasopressin analogues with effect on central nervous system: synthesis and biological properties. Coll. czechoslov. chem. comm. 48, 2862-2873 (1983). TLC of vasopressin analogues on silica with different solvent systems, e.g. butanol -98 % formic acid - water 150:27:23, butanol-25 % NH3 -water 170:15:15. Detection with ninhydrin or by chlorination.

Nachweis mittels DC. (Pure enantiomeric drugs. Identification by densitometry.) Deutsche Apotheker Zeitung 132, 947 –952 (1992). TLC of amino acids, a-methyl amino acids on chiral plates and RP-18 silica with methanol – water – acetonitrile 1:1:4 and 5:5:3, also with methanol – water 1:8 and acetone – methanol – water 10:2:2). Detection by spraying with 0,3% ninhydrin in acetone.

J. Planar Chromatogr. 13, 160-165 (2000). TLC of a-amino acids in small peptides; after sequential acid hydrolysis of a peptide, derivatization of the free amino acids with dansyl chloride, purification of the resulting DNS-amino acids by TLC, and stereochemical analysis by reversed-phase TLC. Purificatiom of DNS-amino acids (DNS-D-Arg, DALDA, DNS-Leu, DNS-Val) on silica gel with toluene - pyridine - acetic acid 40:10:1. After extraction stereochemical analysis on RP-18 with e.g. an aqueous solution of b-cyclodextrin containing different proportions of either acetonitrile or methanol, depending on the polarity of the DNS-amino acid. Detection by densitometry at 366 nm.

CBS 101, 2-4 (2008). HPTLC of amino acids (from hydrolysis of peptides) on silica gel, Diol phase, and cellulose with either 2-butanol - acetic acid - pyridine - water 15:3:10:12 or 2-butanol - 25 % ammonia - pyridine - water 39:10:34:26 in a twin-trough chamber or horizontal chamber. Detection by dipping in ninhydrin solution (0.5 % in 2-propanol) followed by heating at 110 °C for 5 min. Better results are achieved by adding ninhydrin directly to the mobile phase at a 0.5 %-level. Quantitative determination by absorbance measurement at 440 nm. Selectivity was better on the cellulose and silica gel plate. Selection of the chromatographic system depended on which amino acids had to be separated and no general recommendation could be given. HPTLC analysis of a hydrolyzed peptide sample (containing Phe, Trp, D-Bal, Apc and Inp) on cellulose with the acidic mobile phase. All five amino acids were quantified between 70 and 130 % of the theoretical value for non-stable amino acids (degradation 5 to 30 %).

J. Planar Chromatogr. 23, 365-368 (2010). HPTLC of palmitoyl hexapeptide (an antiwrinkle peptide) on silica gel with toluene - ethanol 9:1 in a twin-trough chamber with saturation for 30 min at room temperature (25 +/- 2 °C). The hRf was 33. Quantitative determination by absorbance measurement at 211 nm. Linearity was between 10 and 30 ng/band. The LOD and LOQ was 3 and 9 ng/band, respectively. The intra-day precision (%RSD, n = 6) was 0.9-1.5 % and the inter-day precision 0.9-1.4 %. The small %RSD obtained after small changes of the method conditions indicate the method is robust. The recovery of the method was in the range of 98.9-101.3 %.