CBS 109, 10-12 (2012). HPTLC of steviol glycosides (stevioside, rebaudioside, dulcoside A, steviolbioside) on silica gel (pre-washed with methanol and dried at 100 °C for 15 min) with ethyl acetate - methanol - acetic acid 3:1:1 over 60 mm. Detection under white light after immersion in ß-naphthol reagent (2 g in 180 mL ethanol with 12 mL 50 % sulfuric acid) and heating at 120 °C for 5 min. Quantitative absorption measurement at 500 nm after derivatization. LOD was 10 ng/band and LOQ 30 ng/zone. Using the calibration curve method the LOQ was reduced to 12 ng/band via peak height and 20 ng/band via peak area. The calculated expected tolerance range over the whole procedure inclusive sample preparation considered recovery rates at 3 different concentration levels (0.02, 0.13, and 0.20 %) in milk-based matrix. The accuracy (recovery tolerance limit of 92-120 %), repeatability (3.1-5.4 %) and intermediate precision (4.0-8.4 %) were highly satisfying, exemplarily shown for stevioside in milk-based matrix. ANOVA was successfully passed to prove the working range. With the newly developed and validated HPTLC method, steviol glycosides in Stevia leaves, Stevia formulations, and food products were investigated.

J. Liq. Chromatogr. Relat. Technol. 36, 2378-2386 (2013). 2D-HPTLC of testosterone (1), progesterone (2), hydrocortison (3), estriol (4), ethinylestradiol (5), sitosterol (6), estrone (7), prednisolone (8), estradiol (9) and norethindrone (10) in waste water on cyanopropyl silica gel with dichloromethane - methanol - cyclohexane 19:1:12 in the first direction and water - acetonitrile - ethanol - dioxane 8:2:1:1+1 drop ammonia in the second direction. Detection by heating at 110 °C for 1 min followed by dipping into a mixture of sulfuric acid 98 % - water 1:49 and heating at 110°C for 10 min. Quantitative determination by absorbance measurement at 366 nm. The hRf values for the first and second direction were 80 and 5 for (1), 72 and 9 for (2), 32 and 21 for (3), 8 and 31 for (4), 31 and 11 for (5), 80 and 0 for (6), 44 and 12 for (7), 12 and 34 for (8), 71 and 1 for (9) and 62 and 16 for (10). LOD and LOQ for 17alpha-ethinylestradiol were 1 and 2 ng/zone, respectively.

J. Chromatogr. A 1289, 105-118 (2013). HPTLC of 11 anthocyanes named cyanidin (1), delphinidin (2), malvidin (3), peonidin (4), pelargonidin (5), cyanidin-3-glucoside (6), delphinidin-3-glucoside (7), malvidin-3-glucoside (8), peonidin-3-glucoside (9), pelargonidin-3-glucoside (10) and malvidin-3,5-diglucoside (11) in pomace, feed, juice and wine on silica gel with ethyl acetate - toluene - formic acid - water 50:15:4:6 for the anthocyanidins (1) to (5) and ethyl acetate - 2-butanone - formic acid - water 35:15:6:4 for the anthocyanins (6) to (11). Quantitative determination by absorbance measurement using a multi-wavelength scan at 505 nm for (10), 510 nm for (5), 520 nm for (4) and (9), 530 nm for (1), (3), (6), (8) and (11) and 555 nm for (7). Detection was compared by dipping into a DPPH radical reagent solution (0.5 mM methanolic solution of the DPPH) and into Aliivibrio fischeri bioassay suspension. Linearity was in the range of 180-540 ng/zone for (1), 47-141 ng/zone for (2), 147-441 ng/zone for (3), 24-89 ng/zone for (4), 32-95 ng/zone for (5), 71-343 ng/zone for (6), 63-304 ng/zone for (7), 40-191 ng/zone for (8), 27-131 ng/zone for (9), 16-76 ng/zone for (10) and 45-219 ng/zone for (11). The intermediate precision over several months was below 6.7 % (n=3). The LODs of the anthocyanidins were much better compared to those for anthocyanins. The LOQs for (1) to (11) were below 90 ng/zone, most even below 30 ng/zone and for (9) and (10), the LOQ were even below 7 ng/zone. Radical scavenging as well as bioactivity properties were important complementary detection methods.

J. Liq. Chromatogr. Relat. Technol. 37, 1416-1426 (2014). HPTLC of lumefantrine (1) and artemether (2) on silica gel with toluene – ethyl acetate – acetic acid 4:15:5. Detection by dipping into a derivatization reagent (10 % each of methanolic concentrated sulfuric acid and anisaldehyde), followed by heating at 110 °C for 3 min. Quantitative determination by absorbance measurement at 519 nm. The hRF values for (1) and (2) were 55 and 70, respectively. Linearity was in the range of 60-360 ng/zone for (1) and 10-60 ng/zone for (2). The intermediate/interday/intra-day precisions were below 1 % (n=3). The LOD and LOQ were 7 and 26 ng/zone for (1) and 2 and 6 ng/zone for (2), respectively. Recoveries were between 97.6-101.3 % for both (1) and (2).

Chromatogr. Res. Int. 10, 1-11 (2014). HPTLC of artemisinin of Indian Artemisia annua L. was performed on HPTLC foil silica gel with n-hexane - ethyl acetate 3:1 in a twin-trough chamber up to a migration distance of 85 mm. Detection with anisaldehyde sulphuric acid reagent followed by heating at 110 °C for 10–15 min. Quantitative determination of artemisinin by densitometry at 540 nm. The hRf value of artemisinin (pink colored) was 28. The linearity was between 400 to 2800 ng/spot with a correlation coefficient of 0.9975. The precision (%RSD) was ≤3.3% (n=3). The LOD and LOQ were 40 ng/zone and 80 ng/zone, respectively. Recoveries were between 74 and 105 % for 0.6 mg/mL. Artemisinin content was highest in the leaf extract; no artemisinin was detected in the root extract.

J. of Chromatogr. Sci. 53 (2), 338-344 (2014). Presentation of a method for the simultaneous quantification of three glycosidic isoflavones (daidzin, genistin and glycitin) in soybean (Glycine max L.) by HPTLC on silica gel with toluene – ethyl acetate – formic acid – acetic acid 2:16:2:1. The hRf values of daidzin (1), genistin (2) and glycitin (3) were 39, 51 and 32, respectively. Detection and quantification by densitometry at 260 nm. Validation in accordance with the ICH guidelines with the results for precision of ≤2.1 %, ≤0.7 % and ≤0.1 %, recovery of 95.9-106.7 %, 86.9-106.6 % and 98.5-105.6 %, LOD of 3, 19 and 4 µg/mL and LOQ of 9, 59 and 11 µg/mL for the glycosidic forms of (1), (2), and (3). The method was used for the analysis of the soybean variety Kh-09 bragg which showed high amounts of glycosidic isoflavones: 278, 598 and 109 µg/g for (1), (2), and (3). After fermentation with Bacillus subtilis, the concentration of glycosidic isoflavones significantly decreased while those of the aglycone isoflavones increased.

root extract via HPTLC–UV/Vis/FLD–EDA–MS. J. Planar Chromatogr. 31, 79-86 (2018). HPTLC with effect-directed analysis (EDA) for (bio)profiling of Pimpinella saxifraga root. HPTLC on silica gel with 1) ethyl acetate – methanol – acetic acid 8:3:1 for polar separation, and 2) toluene – ethyl acetate – acetic acid 20:5:1 for apolar separation. Ten different detections were shown on one HPTLC plate cut into sections. Detection of absorbing compounds under A) white light and B) UV 254 nm and C) fluorescent ones under UV 366 nm. Three plate sections were used for microchemical derivatizations for D) detection of flavonoids after derivatization with diphenylborinic acid 2-aminoethylester reagent, followed by dipping into a polyethylene glycol 400 solution, E) universal detection with anisaldehyde sulfuric acid reagent, and F) detection of glycosides with diphenylamine aniline reagent. Effect-directed detection of G) DPPH scavenging compounds, antimicrobials via H) A. fischeri and I) B. subtilis bioassays, and J) AChE inhibitory compounds was also performed. Multi-detection showed multi-potent zones with hRF values of 19, 24, 49 and 78, which were exemplarily further characterized by HPTLC–ESI–MS in both ionization modes. A weak estrogen-effective zone was also observed via HPTLC–planar yeast estrogen screen (pYES) bioassay on RP-18 with n-hexane – toluene – ethyl acetate 6:3:4 or, after optimization, toluene – ethyl acetate 1:1.

J. Sep. Sci. 1-9 (2017). HPTLC of canagliflozin (1) and its degradation product (2) on silica gel with acetone – ethanol 4:1. Quantitative determination by absorbance measurement at 290 nm. The hRF values for (1) and (2) were 64 and 81, respectively. Linearity was between 0.4 and 3.6 μg/zone for (1) and 0.2 and 3.2 μg/zone for (2). LOD and LOQ were 70 and 200 ng/zone for (2). The intermediate/interday/intra-day precisions were below 2 %. Average recovery was 100.7 % for (1) and 99.4 % for (2).