J. Sep. Sci. 36, 2703-2708 (2013). HPTLC of biotin in Euphausia superba on silica gel with dichloromethane - 2-propanol - methanol 3:3:2 + 1 drop glacial acetic acid. Detection (1) by spraying with 0.1 - 1 % 4-(dimethylamino)cinnamaldehyde and sulfuric acid in ethanol, followed by drying for 5 min and spraying with liquid paraffin - chloroform 1:10. Alternatively, biotin was detected (2) by spraying with 0.05 % potassium permanganate. Quantitative determination by absorbance measurement at 530 nm for (1) and 400 nm for (2). The hRf value of biotin was 50. Linearity was in the range of 340-3310 ng/zone for both (1) and (2). LOD and LOQ were 50 and 90 ng/zone for (1) and 60 and 100 ng/zone for (2). Average recoveries were 99.6 % for (1) and 99.7 % for (2). Intermediate intra- and inter-day precision was below 2 % (n=3).

Planta Medica 82, 11/12, 973-985 (2016). TLC was applied for three purposes in the study on the activity of Ephedra sinica aerial parts against the X-linked inhibitor of apoptosis protein. First, an alkaloid-enriched fraction obtained according to Reti’s method (1953) was controlled with Dragendorff’s reagent on TLC (layer, eluent unknown). Second, the column fractionations of the ethanol extracts were monitored by TLC on silica gel with petroleum ether – ethyl acetate – methanol 6:4:1, detection with vanillin - sulfuric acid reagent. Third, to allow the determination of the polymerization degree of proanthocyanidins of one active fraction, a subfraction was incubated 6 h at 50 °C in methanol with hydrochloric acid and benzylmercaptan. This thiolytical degradation was monitored by TLC on silica gel with toluene – ethyl acetate – methanol – ethanol – acetic acid – water 20:16:2:2:4:1, detection with vanillin - sulfuric acid reagent; the reaction was found complete, giving thioether adducts for each catechic unit (mere flavanols for the terminal unit), the products were identified and quantified by HPLC-MS._x000D_

Planta Medica 82(15), 1359-1367 (2016). The presence of hispidin (a styryl pyrone) and hispolon in a methanolic Soxhlet extract of powdered Inonotus hispidus was verified by TLC on silica gel with ethyl acetate – methanol - water 200:27:20. Detection under UV light before and after derivatization with Natural Product/PEG reagent, and with anisaldehyde sulfuric acid reagent (followed by heating for 5 min at 110 °C). The two phenolic compounds were confirmed and quantified by HPLC.

Phytochem. Anal. 28, 87-92 (2017). HPTLC fingerprint of the aerial parts of Justicia secunda on silica gel with chloroform – methanol – water 6:4:1. Detection by dipping into 200 mL enzyme solution (2000 U of alpha-D-glucosidase dissolved in 200 mL buffer solution prepared with 10 g sodium acetate in 250 mL double-distilled water, pH 7.5 with acetic acid), followed by incubation for 1 h in a humid desiccator and dipping into 200 mL of substrate solution (2 mg/mL 2-naphthyl-alpha-D-glucopyranoside in 50 % aqueous ethanol and 2.5 mg/mL Fast blue salt B in double-distilled water, mixed 1:1 before applying). Detection under UV 366 nm.

CBS 120, 14-15 (2018). The drugs cefixime trihydrate (CEFI) and azithromycin dihydrate (AZI) were subjected to hydrolytic degradation (with water, 0.5 N HCl or 0.5 N NaOH), oxidative degradation (with 3 % and 30 % hydrogen peroxide), thermal degradation (heated at 100 °C and 200 °C for 1 h and 2 h) and photolytic degradation (exposed to fluorescent cold white light and UV light). HPTLC of CEFI, AZI, and the degradation samples on silica gel with ethyl acetate – methanol – acetone –_x000D_ toluene – ammonia 2:10:14:1:1 to the migration distance of 80 mm. Detection of AZI by immersion into sulfuric acid reagent (1:4 in ethanol) and heating at 100 °C for 5 min. Evaluation under UV 254 nm, UV 366 nm, and white light. Quantitative determination by absorbance measurement at 235 nm for CEFI and 530 nm for AZI. Linearity was in the range of 500–2500 ng/zone for CEFI and 50–250 ng/zone for AZI. The LOD and LOQ (ng/zone) for CEFI were 58 and 175, respectively, and for AZI 3 and 10, respectively. Precision (%RSD) was <2 %. In the forced degradation studies, CEFI degraded to 4 major products under different stress conditions. AZI showed only one additional peak upon acid and neutral hydrolysis.

J. Planar Chromatogr. 3, 370-375 (1990). The influence of derivatization technique, plate drying, reagent concentration, and selected detector parameters on the densitometric determination of flavonoids was investigated using the two main flavonoid glucoronides from Malva silvestris leaves as an example. Postchromatographic derivatization by dipping successively in 0.5 % NST (2-aminoethyl diphenylborinate) in ethyl acetate and 5 % polyethylene glycol in dichloromethane. The method is also appropriate for the quantitative determination of flavonoids.

Planar Chromatogr. 3 79-81 (1990). TLC separation of lanthanides and other elements (Ce, Nd, Sm, Gd, Ho, Yb, Y, Ti, V, Zr, Th, U) on silica impregnated with different concentrations of H2MEHP, using different concentrations of nitric acid (0.05 - 3.0 M). Detection by spraying with 1% solution of 8-hydroxyquinoline in ethanol, followed by exposure to NH3.

Chinese J. Chromatogr. 10, 169-170 (1992). TLC of gangliosides on silica with 1) chloroform – methanol – water 11:9:2, 2) acetic acid – propanol – chloroform – methanol – water 5:4:4:4:3, 3) chloroform – methanol – NH3 40:32:7. Detection by spraying with a solution containing 0.2 g resorcinol, water 10 mL, hydrochloric acid (36 %) 80 mL, 0.1 mol/L copper sulfate, and heating for 15 – 20 min at 110 °C.