J Chromatogr A 1653, 462442 (2021). Samples were peptides obtained through tryptic hydrolysis of the 5 most abundant milk proteins: α-lactalbumin (α-LA), β-lactoglobulin (β-LG), α-, β- and κ-casein (CA). As standards, synthetic whey and pea (Pisum sativum, Fabaceae) peptides (selected based on the in silico tryptic digest of α-LA, β-LG, legumin A, and vicilin with one or zero miscleavages) were only used in the last assay for prediction of the RF values of peptides with known amino-acid (AA) sequences. Two-dimensional HPTLC on silica gel (pre-washed with methanol and activated 10 min at 100°), first with basic mobile phase sec-butanol – pyridine – ammonia – water 39:34:10:26, and (after 12h drying) in the orthogonal direction with acidic mobile phase sec-butanol – pyridine – acetic acid – water 11:8:2:5. Derivatization for peptides and proteins by immersion into fluorescamine (0.05 % in acetone); visualization under UV 254 nm and 365 nm. Computer-assisted determination of the x- and y-coordinates of the derivatized zones. Repeatability (n=8) of the 2D-HPTLC was statistically tested with the Kolmogorov-Smirnov test for normal distribution and with Dixon’s Q test for outliers. Relative standard deviation (RSD) for the RF values was 12.9 % for the first dimension (y-coordinates) and 16.5 % for the second dimension (x-coordinates). According to their higher intensity and sharpness, 15 – 20 detected zones from each protein hydrolyzate were selected, manually scraped from the derivatized layer, dissolved in formic acid solution (0.1 % in acetonitrile – water 3:2), mixed with an equal volume of matrix (dihydroxybenzoic acid 2 % in acetonitrile – water 3:7), crystallized on air on a ground steel target, before being desorbed by the laser beam of the MALDI-TOF-MS/MS (matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry). Direct hyphenation of HPTLC to MS was not performed, to avoid zone diffusion during plate coating with the matrix and to circumvent the stronger binding of polar peptides on the layer.  The MS spectra were acquired in positive reflector mode in m/z range 340 – 4000 (10 – 2500 for fragments), using an external peptide as calibration standard. Identification of 51 from the 85 selected peptides according to AA sequences was performed, using software programs allowing m/z calculation of protein fragments and estimation of cleavage sites. Correlation of the retention behaviour of the peptides with their properties (molecular weight MW, isoelectric point IEP, charges, polarity) was tested with Student’s two-sided t-test after calculation of Pearson’s correlation coefficients. The correlation was significant with IEP, percentages of anionic AA and of non-polar AA; but not with the following properties: MW, percentages of cationic AA and of uncharged polar AA. Finally, based on the correlation results, regression formulas were found to calculate the x- and y-coordinates of any known peptide from the percentage of non-polar AA (or vice-versa). The prediction power of these formulas was verified by repeating the complete 2D-HPTLC-MS experiment with the standard peptides of whey and of peas, and measuring the absolute and relative deviations between the actual x- and y-coordinates and the predicted values. The absolute deviations were higher in the lower RF zones. The average, relative RF value deviations (range 22.1 – 25.7 %) were not different between whey and pea peptides.

J. Chromatogr. 292, 479-484 (1984). HPTLC of heterogeneous mixtures of dansylated ovalbumine glycopeptides incubated with rat brain homogenates on silica with methyl acetate - chloroform - propanol - methanol - 0.25 % aq. potassium chloride 25:20:20:20:17. Prior to separation, dansyl-L-leucine: is added as internal standard. Fluorescence scanning at 366/>400 nm.

J. Chromatogr. 698, 333-339 (1995). A review with 56 references on the newer applications of electrophoresis in agarose gels, emphasizing on the visualization and quantification of separated lipoproteins, on the use of agarose gel electrophoresis for the detection and quantification of apolipoproteins of the separated lipoproteins, and on the detection of lipoprotein heterogeneity. Discussion of two-dimensional electrophoretic analysis of lipoprotein.

Biomed Chromatogr. 11, 160-163 (1997). TLC on silica gel with butanol - ethanol - water 4:3:3. Detection by spraying with Dragendorff's reagent. Investigation of TLC behavior of the liposomes. Use of the TLC method in administration of the liposomes for targeting the physiological intracellular effects of reninangiotensin system compounds.

Proc. Intern. Symposium on TLC with special emphasis on OPLC, Szeged, 74, (1984). OPLC (OPTLC) of amino acids on ion-exchange layers with sodium citrate buffer pH 3.15. Detection with ninhydrin reagent. Densitometry by absorbance at 535 nm ; detection limit 0.5-1.0 nmol.

J. Chromatogr. 698, 263-279 (1995). A review with 145 references on the major extraction and gel electrophoretic procedures available for the study of plant proteins. Discussion of some techniques for the extraction of plant proteins, of the utility of gel electrophoresis for the study of plant enzymes, and of some techniques to study plant defense proteins. Description of the techniques allowing the specific detection of hydrolases acting on microbial cell walls.

J. Chromatogr. A 816, 97-105 (1998). Use of adsorption TLC to separate proteins with albumin, transferrin, lactoferrin and lysozyme as the model compounds on DEAE anion exchanger with solution containing sodium phosphate, 0.01 M bicine and sodium chloride, Optimization of the pH values for the separation, giving pH 8.5 as the optimum.

Acta Pharm. Jugoslavica 37, 165-173 (1987). TLC of title compounds on silica with benzene - ethyl acetate 1:1. Detection by spraying with iodine-potassium iodide.