62nd Indian Pharmaceutical Congress Abstract No. F-330 (2010). TLC of ofloxacin and ornidazole on silica gel with 1,4-dioxane – ethyl acetate – toluene – glacial acetic acid – water 5:5:3:2:2. The hRf values were 16 and 89 for ofloxacin and ornidazole, respectively. Quantitative determination by absorbance measurement at 287 nm. The results by TLC were comparable to the results by a spectophotometric method.

CBS 107, 13-15 (2011). HPTLC of 5-hydroxymethylfurfural (HMF) in honey on silica gel, prewashed with methanol - water 6:1, with ethyl acetate. Quantitative determination by densitometry in absorbance mode at 290 nm. Optional detection by immersion in p-aminobenzoic acid reagent followed by heating at 110 °C for 5-10 min. The hRf value of HMF was 80. The calibration function was polynomial in the range of 0.8-80 ng/band whilst Michaelis Menten 2 regression was suitable for higher concentrations. The LOD of HMF in honey samples was 0.75 mg/kg (12 µL applied) and the LOQ 2.4 mg/kg. The method complies with the requirement of max. 15 mg/kg of HMF in honey. The results with this method were compared with those obtained by the spectrophotometric Winkler method and by HPLC-UV and mean differences were minor (3.3 % or 0.9 mg/kg). Complementary confirmation by HPTLC-MS online coupling. HMF zones identified under UV were eluted and analyzed by ESI-MS in full-scan and SIM mode.

J. Liq. Chromatogr. Relat. Technol. 35, 1444-1451 (2012). HPTLC of eight new p-toluenesulfonyl-hydrazinothiazole and hydrazine-bis-thiazole derivatives on silica gel RP-18 with mixtures of methanol/water in different methanol proportion between 50 to 70% with 5% increments as mobile phase. Quantitative determination by absorbance measurement at 254 nm. A chromatographic hydrophobicity index was determined and comparable results were obtained using HPLC.

Acta Parasitologica 58/1, 1-5 (2013). Review focused on chromatographic methods, mainly TLC or HPTLC, for metabolic profiling of the trematodes Echinostoma caproni and Schistosoma mansoni. More than 12 references each for Schistosoma and for Echinostoma are reviewed.

J. Planar Chromatogr. 26, 427-434 (2013). HPTLC of oseltamivir (1) in pharmaceuticals counterfeited with ascorbic acid (2) on silica gel with methanol - water 3:2 +1 drop ammonia. Quantitative determination by absorbance measurement at 254 nm. The hRf values for (1) and (2) were 70 and 83, respectively. Linearity was between 5 and 14 µg/zone. LOD and LOQ were 2 and 5 µg/zone. Average recovery (by standard addition) was found to be 100.6 %. Intermediate intra- and inter-day precision was below 1.6 %. Comparing with colorimetric method, HPTLC method provided advantages in terms of speed, lower cost, and environmental protection without sacrificing accuracy.

Textile Auxiliaries 10, 47-50 (2013). Staining of textiles often uses several dyes matching in color, and a change in the dye concentration of the staining solution influences the dye uptake rate in the dyeing process, and thus affects the dyeing result. The real-time monitoring of the dye concentration in the dyeing process can reflect the state of dyeing and allows for more reasonable working processes and staining formulas. A TLC method is presented for multi-wavelength scanning of the dyes cationic yellow X-5GL and X-8GL on silica gel without the need for chromatogram development. An oblique projection algorithm was based on the oblique projection theory. This theory describes a multi variable system with data space and establishes a pure signal separation model which allows to differentiate the measured vector spectrum signal of the interested component from the mixed spectrum signal and determine its content by chemometrics. The obtained results were compared with those by using conventional TLC on silica gel developed with ethanol, followed by densitometric evaluation. It was found that the measured precision for the presented method was lower than that of traditional TLC.

J. Chromatogr. Sci. 54 (4), 492-499 (2016). Development of a sensitive and selective analytical method for simultaneous determination of aminoacridine hydrochloride (1) and lidocaine hydrochloride (2) in bulk powder and pharmaceutical formulation by TLC on silica gel with ethyl acetate – methanol – acetic acid 13:6:1. Quantitative determination by fluorescence measurement at 366 nm for (1) and by absorbance measurement at 220 nm for (2). The calibration curve was in the range of 25–250 ng/zone for (1) and 0.99–9.90 µg/zone for (2).

J. Planar Chromatogr. 31, 397-403 (2018). HPTLC of clozapine (1) and aripiprazole (2) on silica gel with toluene ‒ methanol ‒ ethyl acetate ‒ ammonia 65:25:10:1. Quantitative determination by absorbance measurement at 218 nm. The hRF values for (1) and (2) were 43 and 60, respectively. Linearity was between 200 and 1600 ng/zone for (1) and 100 and 800 ng/zone for (2). LOD and LOQ were 34 and 103 ng/zone for (1) and 20 and 60 ng/zone for (2), respectively. The intermediate precision was <2 % (n=3). Recovery ranged between 98.2-99.9 % for (1) and 98.7-99.5 % for (2).