J Chromatogr A, 1669, 462942 (2022). Samples were medroxyprogesterone acetate (MPA) as standards and commercial drug extracts, dissolved in dichloromethane. TLC on silica gel (preactivated by 30 min heating at 120 °C) with dichloromethane – ethyl acetate 10:1, followed by 30 min drying at 120 °C. Derivatization by spraying with sulfuric acid (50 % in ethanol). Visualization in a 3D-printed chamber designed especially for this purpose, blocking extraneous light and including a smartphone holder, a fluorescent lamp and an optical density step tablet. Pictures were taken with the smartphone digital camera, after spraying (6 background images) and after 10 min heating at 120 °C (6 foreground images). In the last case, MPA appeared as black spots (hRF 16–20). Using an image processing software program: (1) one averaged background image and one averaged foreground image were created by concatenation and were split into 3 colour channels; (2) the green colour channels were corrected to remove background noise, by subtraction of an averaged darkfield image (taken on blank plate without light) and by comparison ratio to an averaged blankfield image (taken on blank plate with light); (3) the pixel values of the MPA bands were converted to optical density values through the Robard’s function, by comparison to a reference image of a theoretical optical density step tablet; (4)  furthermore, the corrected background image was subtracted from the corrected (and denoised with a Gaussian Blur) foreground image; a triangle threshold algorithm was applied on the resulting image, and was converted to a mask (white spots on black background); (5) applying the binary mask to the original corrected images (obtained in (2)), the final integrated density values of MPA spots were obtained. This method was validated for linearity range (1.25–3.75 mg/mL), for precision, for reproducibility, for robustness, and for accuracy expressed as average recovery values (101 % overall mean) by comparison of TLC results with HPLC-DAD results.

J. Planar Chromatogr. 32, 197-203 (2019). HPTLC of equol (1), artemisinin (2) and caffeine (3) on silica gel with methyl t-butyl ether - cyclohexane 1:1 for (1), cyclohexane - ethyl acetate 7:3 for (2) and ethyl acetate - acetone 7:3 for (3). The plate was scanned with a DART–TOF MS system to optimize the measurement conditions. The hRF values for (1) to (3) were 71, 63 and 53, respectively. LOD and LOQ were 1.2 and 1.8 µg/zone for (1), 225 and 315 ng/zone for (2) and 270 and 490 ng/zone for (3), respectivley.

Phytochem. Anal. 24, 303-308 (2013). HPTLC of chicoric acid (1), chlorogenic acid (2) and echinacoside (3) in commercial Echinacea products on silica gel with ethyl acetate - formic acid - acetic acid - water 100:11:11:17. Qualitative identification under UV 366 nm. Images were quantified and transformed into chromatograms, as signal intensities (peaks) versus hRf (retention factor) for a artificial neural network (ANN) correlation. LOD were 19, 46 and 29 ng/band, whereas LOQ were 63, 154 and 98 ng/band for (1), (2) and (3), respectively.

R.E. Kaiser (Ed) "Proc. of the 3rd Int. Symp. on Instr. HPTLC, Wuerzburg" IfC, Bad Duerkheim 1985, 373-380.Description of the method,, which can be used for detection, identification and quantification in both absorbance and fluorescence. Application example from drug analysis (anthraquinone type, laxative).

Anal. Sci. 3, 11-15 (1987). Description of a photoacoustic densitometry technique by laser beam scanning on a photoacoustic cell without chopping or modulation. Conversion and processing of the photoacoustic signals by microcomputer. The reproducibility of measurement for 0.03 to 0.25 µg Malachite Green was 1.7-4.5% RSD.

Realised in the systems containing binary and ternary mobile phases. Annales Universitatis Mariae Curie- Skodowska XLI 11, 120-127 (1986). Description of a graphical method for the evaluation and comparison of the resolution obtained with binary and ternary solvent mixtures. It is based on position, shape and size of two neighbouring spots and serves for the optimization of the solvent ratio. The method is demonstrated by TLC of aromatic hydrocarbons on silica with mixtures of carbon tetrachloride, benzene, chloroform, dioxane and acetone.

Chem. Anal. (N.Y.) 108, 185-196 (1990). Studies of the measurement of two-dimensional gel electrophoretic and HPTLC patterns. Presentation of two qualitative mapping techniques. Examination of quantitative analysis of partial spots using calibration curves.

Anal. Chem. 64, 3176-3179 (1992). Description of a square-wave anodic stripping voltametric method for ppm determination of heavy metals. Separation by TLC on carboxymethyl cellulose using a cellulose dialysis membrane - covered mercury film electrode placed directly on the TLC plate surface in a thin-film of supporting electrolyte solution. Presentation of the results for a mixture of Pb(II), Cd(II), and Zn(II). Calibration curves for Pb(II).