CBS 110, 2-4 (2013). HPTLC of caffeic acid, chlorogenic acid, and rutin hydrate on silica gel (prewashed with methanol and dried under vacuum at 50 °C for 30 min) with formic acid - ethyl acetate - water - methyl ethyl ketone 5:30:6:18 with chamber saturation for 5 min over a developing distance of 5 cm. Detection under UV 254 nm. Elution of substance zones with TLC-MS Interface using methanol and a flow-rate of 0.3 mL/min for 6 min. Evaporation of methanol under nitrogen, residue taken up with methanol-d4. Subsequent off-line quantitative 1H-NMR spectroscopic analysis of the residue, acquisition time 30 min. Linearity for all substances was confirmed in the range of 10 - 80 µg/mL. Recoveries were in the range of 100.5 % for chlorogenic acid and up to 103.4 % for caffeic acid, with precisions under 3.9 % (%RSD, n=3).

CBS 107, 11-12 (2011) HPTLC of tiliroside (a cosmetic active obtained by extraction from a plant of the family Sterculiaceae) and side components kaempferol-3-glucoside, kaempferol-3-rutinoside, kaempferol, and coumaric acid on silica gel with ethyl acetate - formic acid - acetic acid- water 100:11:11:27 + 1% heptane. Detection under UV 366 nm after spraying with natural products reagent (1 % diphenylborinic acid 2-aminoethylester in methanol) and under white light after spraying with anisaldehyde sulfuric acid reagent (0.5 mL anisaldehyde in 85 mL methanol with 10 mL acetic acid and 8 mL conc. sulfuric acid) and heating at 90-125 °C for 15 min. Quantitative absorption measurement of tiliroside at 315 nm using a 4-point calibration via peak area. The tiliroside contents in the sample extracts were determined as: 1 = 1.09 µg (RSD = 0.4 %), 2 = 0.93 µg (RSD = 0.8 %), 3 = 1.19 µg (RSD = 1.2 %) and 4 = 3.32 µg (RSD = 0.3 %). During the side component analysis no kaempferol, coumaric acid, and glucose were detected in the tiliroside samples. Small amounts of kaempferol-3-glucoside and kaempferol-3-rutinoside were found. HPTLC covers several tasks: quantification of the active ingredient in a complex plant matrix for determining the quality of the raw material, in-process control for monitoring the impurity profile during the manufacturing process and the quantification of the active ingredient in the final product.

J. Planar Chromatogr. 27, 174-180 (2014). HPTLC of betulinic acid (1), 24beta-ethylcholesta-5,22E,25-triene-3beta-ol (2) and lupeol (3) in Clerodendrum phlomidis on silica gel with chloroform - methanol 49:1. Detection by dipping into vanillin - sulfuric acid reagent (vanillin - ethanol - sulfuric acid 1:95:5, w/V/V), followed by heating at 110 ºC for 3 min. Quantitative determination by absorbance measurement at 600 nm. The hRF values for (1) to (3) were 30, 52 and 70. Linearity was in the range of 300-1500 ng/mL. The intermediate/interday/intra-day precisions were below 2 % (n=5). The LOD and LOQ were 22 and 74 ng/zone for (1), 20 and 66 ng/zone for (2) and 30 and 100 ng/zone for (3), respectively. Average recovery was 99.0 % for (1), 98.5 % for (2) and 98.2 % for (3).

J. Liq. Chromatogr. Relat. Technol. 37, 1114-1132 (2014). HPTLC of rosuvastatin on silica gel with chloroform - n-hexane - methanol - glacial acetic acid 80:100:40:15:1. Quantitative determination by absorbance measurement at 295 nm. The hRf value for rosuvastatin was 9. Degradation products (DPs) were characterized by ESI-MS. For acidic hydrolysis, 4 major DPs with hRF values of 16, 27, 74 and 77 were obtained. For alkaline hydrolysis, one major DP of hRF 73 was detected. For thermal hydrolysis two major DPs with hRF 74 and 77 were detected. For exposure to hydrogen peroxide, 5 major DPs with hRF 15, 25, 30, 71 and 77 were obtained. For photolytic hydrolysis, 2 major DPs with hRF 70 and 78 were detected. Linearity was in the range of 500-20000 ng/zone. The intermediate/interday/intra-day precisions were below 2 % (n=3). The LOD and LOQ were 170 and 500 ng/zone. Average recovery was 99.9 %.

Braz. J. Pharm. Sci. 49, 845-851 (2013). HPTLC of metoprolol (1) and hydrochlorothiazide (2) in human plasma on silica gel with chloroform - methanol - ammonia 18:2:1. Quantitative determination by absorbance measurement at 239 nm. The hRF values for (1) and (2) were 48 and 13. Linearity was in the range of 20-120 μg/zone for (1) and 2-12 μg/zone for (2). The intermediate/interday/intra-day precisions were below 5 % (n=3). The LOQs were 20 and 2 μg/zone for (1) and (2), respectively. Recoveries were between 70.6 and 84.9 %.

J. Liq. Chromatogr. Relat. Technol. 38, 1279-1285 (2015). TLC of Citrus herbal medicines on NaOH-modified silica gel with ethyl acetate - methanol - water 100:17:13, followed by drying at room temperature and second development with toluene - ethyl acetate - formic acid - water 20:10:1:1. Detection by spraying with 1 % aluminium chloride ethanolic solution. The greyscale image captured under UV 365 nm was corrected by removing the quadratic baseline trend of the densitometric curve of every row.

J. Chromatogr. Sci. 54 (1), 70-78 (2016). HPTLC of flurbiprofen and chloramphenicol in the presence of their degradation products, produced in acidic, alkaline, neutral, oxidative, photolytic and thermal stress conditions, on silica gel with ethyl acetate – n-hexane – methanol – triethylamine 10:8:4:1. The hRf of flurbiprofen was 29 and of chloramphenicol 62. Quantitative determination by densitometry at 267 nm. Linearity was between 12 and 60 ng/zone with a correlation coefficient of 0.9997 for flurbiprofen and between 200 and 1000 ng/zone with a correlation coefficient of 0.9977 for chloramphenicol. The application of the method to the estimation of flurbiprofen and chloramphenicol in commercial ophthalmic formulation indicated that the method was specific, accurate, reproducible and suitable for routine analysis of flurbiprofen and chloramphenicol in the presence of their degradation products in their individual as well as combined pharmaceutical formulations.

J. Chromatogr. Sci. 55 (10), 1059-1065 (2017). Presentation of a new high-throughput method for the simultaneous analysis of isoflavones and soyasaponins in soy (Glycine max L.) products by HPTLC on silica gel with ethyl acetate – methanol – water – acetic acid 100:20:16:1. Detection by treatment with anisaldehyde sulfuric acid reagent. Quantitative determination by densitometric multi-wavelength scanning at UV 265 nm for genistin, daidzin and glycitin and at 650 nm for soyasaponins I and III. The correlation coefficient of the linear calibration curve was >0.994. Intra-day precision (%RSD) of substances in matrix was between 0.7-0.9 %, inter-day precision (%RSD) was between 1.2-1.8 %). The method was suitable for the determination of the studied analytes in soy-based infant formula and soybean products.