J. AOAC Int. 102, 1021-1026 (2019). HPTLC of reserpine (1), atropine (2) and piperine (3) in Sarpagandha Ghanvati on silica gel with toluene - ethyl acetate - diethyl amine 7:2:1. Quantitative determination by absorbance measurement at 269 nm for (1), 220 nm for (2) and 254 nm for (3), respectively. The hRF values for (1) to (3) were 57, 30 and 92, respectively. Linearity was between 200 and 600 ng/zone for (1), 1000 and 5000 ng/zone for (2) and 100 and 500 ng/zone for (3), respectively. Intermediate precision was below 1 % (n=3). The LOD and LOQ were 60 and 200 ng/zone for (1), 600 and 800 ng/zone for (2) and 20 and 10 ng/zone for (3), respectively. Recovery rate was 98.9 % for (1), 99.5 % for (2) and 99.1 % for (3). The recovery from the formulation was 90.3 %, 92.4 % and 90.0 % of the expected values of (1) to (3), respectively.

J. AOAC Int. 102, 1003-1013 (2019). HPTLC of quercetin (1) and berberine (2) in Pushyanuga Churna on silica gel with toluene - ethyl acetate - methanol - formic acid 6:6:2:1. Quantitative determination by absorbance measurement at 254 nm for (1) and 366 nm for (2). The hRF values for (1) and (2) were 63 and 24, respectively. Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 1 and 3 µg/mL for (1) and 0.05 and 0.1 µg/mL for (2), respectively. Recovery rate was between 93.5 and 100.6 % for (1) and 95.2 and 97.6 % for (2).

J. AOAC Int. 102, 1014-1020 (2019). HPTLC of asiaticoside in Centella asiatica on silica gel with toluene - ethyl acetate - methanol - glacial acetic acid 2:7:3:1. Detection by spraying with anisaldehyde sulfuric acid reagent. Quantitative determination by absorbance measurement at 595 nm. The hRF values for asiaticoside were between 43 and 47 in the standard, plant powder and marketed formulations. Linearity was between 200 and 1800 ng/zone. Intermediate precisions were below 2 % (n=6). The LOD and LOQ were 51 and 155 ng/zone. Recovery rate was between 97.7 and 105.5 %.

J. of Modern Trad. Chinese Med. 20 (8), 975-978 (2018). Panax notoginseng is a traditional Chinese medicinal herb which activates blood circulation, anti-platelet aggregation and anti-thrombosis. TLC for quality control of ginsenoside Rb1 (1), notoginsenoside R1 (2) and ginsenoside Rg1 (3) on silica gel with the lower phase of chloroform – methanol – water 13:7:2 (after standing for 12 h at below 10˚C). Detection by spraying with 10% sulfuric acid in ethanol and heating at 110 ˚C until the zones are visible, evaluation under UV 365 nm. Quantification by densitometric absorption measurement at 510 nm. Validation by investigation of the linearity ranges of 0.5-5.0 µg/zone (r=0.998) for (1), 0.5-5.01 µg/zone (r=0.999) for (2) and 0.5-4.9 µg/zone (r=0.998) for (3). The plate-to-plate precision % RSD (n=12) was 1.5 %, 1.1 % and 1.9 % for (1) to (3). Recovery from standard sample addition was 96.4 % (%RSD 1.4 %, n=6) for (1), 96.9 % (%RSD 0.9 %, n=6) for (2), and 98.9% (%RSD 1.7 %, n=6) for (3).

J. of Chromatogr. A 1534, 170-178 (2018). HPTLC of flavonoid aglycones in eleven commercial Cistus incanus herbal teas using three independent methods (multi-development on amino phase and two two-dimensional developments on silica gel phase). HPTLC on silica gel with chloroform - methanol - ethyl acetate 15:3:2. Detection at UV 254 and 366 nm and by derivatization with aluminium chloride (1 % methanolic solution), ferric chloride (0.5 g FeCl₃ in 2.5 mL water and 47.5 mL ethanol), NP-PEG (0.5 % methanolic NP solution, and after drying, 5 % ethanolic PEG solution), PABA (0.5 g PABA in 18 mL glacial acetic acid diluted with 20 mL water, plus 1 mL o-phosphoric acid and 60 mL acetone), or DPA reagents (1 g aniline and 1 g diphenylamine in 100 mL acetone and 10 mL o-phosphoric acid, heated for 5 min at 110°C). Confirmation of the presence of glucose by HPTLC on amino phase with in situ acid hydrolysis: incubation in HCl vapor followed by heating at 100°C, pre-development with acetonitrile, drying, development with acetonitrile - water 7:3, heating for 20 min at 170°C and dipping in paraffin - n-hexane 1:2 follwed by drying. TLC-direct bioautography by immersion of the developed and dried plates in a bacterial cell suspension of either Bacillus subtilis or Aliivirio fischeri strains. Analysis of the compounds isolated from the bioactive zones by HPLC-diode array detector (DAD)-electrospray ionization (ESI)-MS. The presented TLC/HPTLC platform allowed identification of the antibacterial components apigenin, kaempferide, cis- and trans-tiliroside, and the isomers of the p-coumaric acid-conjugated tiliroside,  all of them inhibiting both B. subtilis and A. fischeri.

Rev. Bras. Farmacogn. 29, 177-181 (2019). HPTLC of chlorogenic acid (1), 3,4-O-dicaffeoylquinic acid (2), and 3,5-O-dicaffeoylquinic acid (3) in the leaves of Pluchea indica on silica gel with ethyl acetate - water - formic acid - toluene 20:2:2:1. Quantitative determination by absorbance measurement at 326 nm. The hRF values for (1) to (3) were 34, 63 and 79, respectively. Linearity was between 100 and 400 ng/zone for (1) to (3). Intermediate precisions were below 3 % (n=3). The LOD and LOQ were 9.9 and 30.1 ng/zone for (1), 17.6 and 53.3 ng/zone for (2) and 6.7 and 20.2 ng/zone for (3), respectively. Recovery rate was 99.0 % for (1), 97.5 % for (2) and 99.6 % for (3).

Food Control. 103, 111-118 (2019). Thin layer chromatography in tandem with surface-enhanced Raman scattering (TLC-SERS) of histamine in tuna samples on diatomaceous earth plates with ethanol - ammonia 3:1. Detection by spraying with Pauly's reagent (equal mixture of 20 mM sulfanilic acid in a 1 M HCl solution and 200 mM sodium nitrite solution, followed by adding 10 % anhydrous sodium carbonate in a 5 % ethanol solution). Gold nanoparticles were deposited on the plate zone and measurements were performed using a Raman spectrometer with an excitation laser wavelength of 785 nm.

Food Chem. 288, 1-7 (2019). HPTLC of sesamin (1) and sesamolin (2) in sesame seed extracts on silica gel with n-pentane - diethyl ether 3:2. Quantitative determination by absorbance measurement at 290 nm. Linearity was between 25 and 150 µg/mL for (1) and 12.5 and 75 µg/mL for (2). Intermediate precision was below 3 % (n=6). The LOD and LOQ were 1.3 and 4 µg/mL for (1) and 0.4 and 1 µg/mL for (2), respectively. Recovery rate was  between 95 and 105 % for (1) and (2). Correlation of the HPTLC and a HPLC-PDA method was notably high.