J. AOAC Int. 100, 414-421 (2017). HPTLC of two binary mixtures containing pyridoxine hydrochloride (1) with either cyclizine hydrochloride (2) or meclizine hydrochloride (3) on silica gel with dichloromethane – acetone – methanol 14:2:1. Quantitative determination by absorbance measurement at 220 nm. The hRF values for (1-3) were 7, 25 and 80, respectively. Linearity was in the range of 0.2-5 μg/zone for (1) and 0.2-4 μg/zone for (2) and (3). The LOD and LOQ were 60 and 190 ng/zone for (1), 50 and 170 ng/zone for (2) and 60 and 170 ng/zone for (3), respectively. The intermediate precision was <2 % (n=3). Average recovery rate was 99.9 % for (1) and (3) and 100.1 % for (2).

J. Planar Chromatogr. 30, 340-349 (2017). HPTLC of aripiprazole and its nine impurities as well as ziprasidone and its five impurities on RP-18 with methanol (1) or ethanol (2) as organic modifiers in the mobile phase. When methanol was used as organic modifier, the mobile phase with the lowest content of methanol was methanol – water – ammonia solution 25 % 13:6:1 and the mobile phase with the highest content of methanol was methanol – water – ammonia solution 25 % 17:2:1. When ethanol was used as organic modifier, the mobile phase with the lowest content of ethanol was ethanol – water – ammonia solution 25 % 12:7:1 and the mobile phase with the highest content of ethanol was ethanol – water – ammonia solution 25 % 16:3:1. Lipophilicity was estimated to develop the quantitative structure–retention relationship (QSRR) models which enabled fast and reliable prediction of the retention behavior.

J. Planar Chromatogr. 30, 363-374 (2017). HPTLC of acetylsalicylic acid (1) and its related compound salicylic acid (2) on silica gel with n-hexane – diethyl ether – 80 % acetic acid 7:2:1. Good quality densitograms with well separated and symmetric peaks of (1) and (2) were achieved. Detection with the following reagents: Janus blue, bromophenol blue, bromocresol blue, hydrogen peroxide (without heating and with heating to 90 °C during 60 min), 1 % sodium hydroxide (with heating to 45 °C and also with heating to 90 °C during 60 min), brilliant green, malachite green, and thymol blue.

J. Chromatogr. Sci. 55, 961-968 (2017). Presentation of two accurate, precise and highly selective stability-indicating methods for simultaneous determination of benztropine mesylate (BNZ) in presence of its hepatotoxic and carcinogenic degradation product, benzophenone (BPH) either in pure form or in the pharmaceutical formulation without any preliminary separation steps. TLC of BNZ and its degradation product on silica gel with hexane – methylene chloride – triethylamine 25:25:3. Quantitative determination by densitometry at 235 nm. The linearity was between 1.5-10 μg/band and 1-10 μg/band for BNZ and BPH, respectively. UPLC of the mixture on a RP C8 analytical column, quantification using a diode array detector at 210 nm. The linearity with UPLC was 20-200 μg/mL and 5-50 μg/mL for BNZ and BPH, respectively. Comparison of the results showed no significant differences between the TLC and UPLC method regarding both accuracy and precision.

J. Planar Chromatogr. 31, 230-234 (2018). HPTLC of hypoxoside in the roots of Hypoxis hemerocallidea on silica gel with chloroform – methanol – water 35:15:1. Quantitative determination by absorbance measurement at 257 nm. The hRf value for hypoxoside was 30. Linearity was in the range of 0.02-1.80 µg/mL. The LOD and LOQ for hypoxoside were 0.51 µg and 1.65 µg/mL. (Note by the editor: It can not be true that the start of calibration is below the LOD by a factor of 25.) The intermediate precision was below 5 %. Average recovery was 84 %.

– a botanical source of the Ayurvedic drug Jivanti. J. Planar Chromatogr. 31, 150-154 (2018). HPTLC of β-sitosterol (1), lupeol (2), and oleanolic acid (3) in Leptadenia pyrotechnica with toluene – ethyl acetate 9:4 for (1); toluene – ethyl acetate – formic acid 70:30:3 for (2), and toluene – methanol – formic acid 45:20:1 for (3). Detection by spraying with freshly prepared p-anisaldehyde sulfuric acid reagent, followed by heating at 110 °C for 3 min. Quantitative determination by absorbance measurement at 530 and 540 nm. The hRf values for (1) to (3) were 64, 84 and 47, respectively. Linearity was in the range of 2-10 μg/zone for (1) to (3). The intermediate precision was below 0.6 %. The LOD and LOQ were 410 and 1270 ng/zone for (1), 550 and 1680 ng/zone for (2) and 300 and 920 ng/zone for (3), respectively. Average recovery for (1) to (3) was 99 %.

Phytochemistry 157, 92-102 (2019). HPTLC of monogalactosyldiacylglycerol (1) and digalactosyldiacylglycerol (2) in the leaves of basket willow (Salix viminalis L., Salicaceae, Malpighiales), cabbage (Brassica oleracea L., Brassicaceae, Brassicales), pea (Pisum sativum, Fabaceae, Fabales), roseroot (Rhodiola rosea L., Crassulaceae, Saxifragales), meadow buttercup (R. acris L., Ranunculales), garlic (Allium sativum L., Amaryllidaceae, Asparagales) and Ipomoea tricolor Cav. (Convolvulaceae, Solanales) on silica gel with acetone – benzene – water 91:30:8. Qualitative identification under UV light at 254 and 366 nm. The hRF values were 20-26 for (1) and 63-77 for (2).

Pharmacogn. Mag. 14, 437-443 (2018). HPTLC fingerprinting of 7 plant species from northeast Brazil (Anacardium occidentale, Annona muricata, Guazuma ulmifolia, Phyllanthus niruri, Psidium guajava, Punica granatum, and Spondias mombin) using caffeic acid (1), quercetin (2), gallic acid (3) and catechin (4) as chemical markers on silica gel with toluene – ethyl acetate – methanol – formic acid 85% 75:25:25:6. Detection of (1) and (2) by spraying with natural products reagent A + 5 % polyethylene glycol 400. Detection of (3) and (4) by spraying with ferric chloride and vanillin-HCl, respectively. Qualitative evaluation under UV light at 254 and 365 nm. The hRF values for (1), (2) and (4) in Anacardium occidentale were 30, 42 and 21, respectively. The hRF value for (4) in Annona muricata was 16. The hRF values for (1) and (4) in Guazuma ulmifolia were 44 and 20, respectivley. The hRF values for (1) and (4) in Psidium guajava were 3 and 18, respectively. The hRF value for (1) in Punica granatum was 33. The hRF values for (1) to (4) in Spondias mombin were 31, 43, 31 and 17, respectively.