J. Planar Chromatogr. 34, 203-209 (2021). HPTLC of triclosan in toothpaste on silica gel with n-heptane - methyl tert-butyl ether - acetic acid 920:80:1. Detection by spraying with 2,6-dichloroquinone-4-chloroimide in 50 mL methanol, followed by spraying with an aqueous sodium carbonate solution (1 g/10 mL). Plates were scanned using a flatbed scanner. The hRF value for triclosan was 22. Linearity was between 100 and 1000 ng/zone. The LOD and LOQ were 46 and 91 ng/zone, respectively. Average recovery was 93.2 %.

J. AOAC Int. 103, 1167-1172 (2020). HPTLC of aminexil (1), niacinamide (2) and pyridoxine HCl (3) on silica gel with propanol - toluene - 33 % ammonia solution
20:30:1. Quantitative determination by absorbance measurement at 270 nm. Linearity was between 0.25 and 1.25 µg/zone for (1), 2 and 7 µg/zone for (2) and 3 and 7 µg/zone for (3). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 20 and 60 ng/zone for (1), 180 and 540 ng/zone for (2) and 140 and 430 ng/zone for (3), respectively. Average recovery was 100.1 % for (1) and (2) and 101.1 % for (3). 

J. Chromatogr. A 1568, 188-196 (2018). Application of an advantageous combination, the desorption-based direct analysis in real time mass spectrometry (DART-MS) immediately after direct bioautography (DB), i.e., in the presence of microorganisms, bioassay medium and substrate reagent. The method offers a straightforward and efficient mass spectrometric detection of bioactive analytes within the bioautogram. It discriminated microorganism cells and highly polar bioassay medium ingredients which could otherwise stress the MS system. Investigation of DB-DART-MS for bioactive compounds in cosmetics using the Bacillus subtilis and Aliivibrio fischeri bioassays for detection of Gram-positive and Gram-negative antimicrobials, respectively, and the planar yeast estrogen screen for detection of estrogen-effective compounds. Study of the influences of three different bioassay matrices on the analyte response and DB-DART-MS performance on different layers (NP and RP) on the example of parabens in hand creams. Ion suppression was enhanced with increasing culture medium complexity. The mass spectrometric quantification by DB-DART-MS at the ng-level in situ each different bioautogram was verified by comparison to HPTLC-DART-MS. The total paraben content of hand creams 1 and 2 was 0.17–0.20% and 0.30–0.34%, respectively, depending on the method used. It proved that DB-DART-MS is a reliable qantitative bioanalytical hyphenation.

Chinese J. Hospit. Pharm. 29 (8), 686-688 (2009). TLC of the extracts of Yixuean pills on silica gel with 1) chloroform - ethyl acetate - acetone - formic acid 60:25:25:4; 2) n-hexane - chloroform - methanol 15:5:2; 3) ethyl acetate - formic acid - acetic acid - water 15:1:1:2. Detection 1) under UV 254 nm; 2) by exposure to iodine vapor and under UV 254 nm; 3) by spraying with 10 % sulfuric acid in ethanol followed by heating at 105 °C until coloration evaluation under visible light and UV 254 nm.

Chinese J. of Forestry Science 49 (10), 127-134 (2013). Flavonoids in bamboo leaves have free radical scavenging, antioxidant, anti-aging, antibacterial, and anti-inflammatory effects and are used as a component in TCM for regulating blood fat and preventing cardiovascular and cerebrovascular diseases. Bamboo-leaf flavonoids are also used in cosmetics and as feed additive. In order to choose the best bamboo species for extraction of flavonoids and to set up a quality control method, the flavonoids in eleven samples of bamboo leaves of three genera collected from Yunnan, Fujian, Sichuan, Jiangsu and Jiangxi provinces are studied by HPTLC. HPTLC-AMD of sample extracts and the standards isoorientin, orientin, isovitexin, vitexin and tricin on silica gel, cleaned with methanol and methylene chloride and dried at 105 °C, with methanol – ethyl acetate – methylene – formic acid 4:7:9:2 to 50 mm in the first step, with acetone – methanol - ethyl acetate – methylene chloride – formic acid 1:2:7:10:2 to 75 mm in the second step, and with acetone - methanol - ethyl acetate - methylene chloride – formic acid 2:1:6:11:2 to 90 mm in the third step. Detection under UV 366 nm after spraying with 1 % aluminum trichloride in ethanol. Quantification of the flavonoids by densitometry at UV 366 nm via peak area. The quantitative method for different flavonoids was validated by investigation of the linearity (90-1750 ng/zone), the precision (%RSD=1.0-2.0 %, n=3 intra-day; %RSD=0.9-2.0 %, n=3 inter-day), and the repeatability (%RSD=0.9-1.9 %, n=9). The LODs were 25-40 ng/zone, and the recoveries were 81.3-106.9 % (n=3).

Biochemical Systematics and Ecology 22, 596-603 (1994). TLC of biflavones developed twice on silica with toluene - ethyl acetate - formic acid 5:4:1. Inspection under UV 254 nm, then spraying with 1% AlCl3 in methanol: biflavones occur under UV 366 nm as yellow/orange fluorescing spots.

J. Planar Chromatogr. 23, 233-236 (2010). HPTLC of trans-citral and cis-citral in lemongrass oil on silica gel with toluene - ethyl acetate 17:3 in a twin-trough chamber saturated for 15 min (at 25 °C and 55 % RH). Detection by spraying with vanillin-sulfuric acid reagent. Quantitative determination by absorbance measurement at 595 nm. Intra-day and inter-day precision were evaluated by replicate (n = 6) analysis of samples (trans-citral at 450, 900, and 1800 ng/band, and cis-citral at 470, 940, and 1880 ng/band). The linear range was 225-3600 ng/band for trans-citral, and 470-3760 ng/band for cis-citral. The correlation coefficient r was 0.9933 for trans-citral and 0.9937 for cis-citral. Intra-day precision (n = 6) was < 3.56 and 5.66 % for trans- and cis-citral, respectively. Inter-day precision was assessed to be < 3.47 and 5.52 % for trans- and cis-citral by repeating the intra-day assay on three different days. Repeatability of sample application and peak-area measurement was 0.98 %, determined by performing six replicate analyses of the same band (1800 ng/band trans-citral and 1880 ng/band cis-citral). The RSD of recovery of trans and cis-citral was in the ranges 1.36-3.25 and 1.64-3.47, respectively.

J. Planar Chromatogr. 28, 167-172 (2015). TLC of trans-resveratrol in cosmetic raw materials on RP with methanol - water 3:2. The plate is dried for 3 h. Quantitative determination by fluorescence measurement using a deuterium lamp at 340 nm. The hRF value was 38. The LOD and LOQ were 2 and 6 ng/zone, respectively. The presence of trans-resveratrol in the analyzed samples was additionally confirmed by detection with anisaldehyde reagent.