J. Sep. Sci. 45, 3800-3810 (2022). HPTLC of favipiravir (1) and meropenem (2) in human plasma on silica gel with ethyl acetate - methanol - water - formic acid 50:40:15:3. Quantitative determination by absorbance measurement at 300 nm for (1) and (2). The hRF values for (1) and (2) were 34 and 10, respectively. Linearity was between 0.1 and 20 µg/mL for (1) and 10 and 60 µg/mL for (2). Inter-day and intra-day precisions were below 5 % (n=3). The LOQ were 0.1 and 10 µg/mL for (1) and (2), respectively. Mean recovery was 99.7 % for (1) and 98.0 % for (2).

J. Ethnopharmacol. 289, 115035 (2022). HPTLC of Unani pharmacopoeial preparations Itrifal Hakim Ali (1) and Habb-e-Kalaf (2) on silica gel with toluene - ethyl acetate 9:1 for (1) and toluene - ethyl acetate 4:1. Detection under UV light at 254 and 366 nm. 

J. Ethnopharmacol. 295, 115327 (2022). Review of modern applications for the analysis of Rauvolfia species, including traditional uses, phytochemistry, quality control, pharmacological properties, as well as clinical evidence that may be useful in the drug discovery process. The paper described qualitative and quantitative methods, including HPTLC methods for the analysis of targeted and non-targeted compounds in different extracts of plant parts of Rauvolfia species.

Phytochem. Anal. 33, 1018-1027 (2022). HPTLC of an α-amylase inhibitor from the aerial part of Asparagus racemosus Willd on silica gel with n-hexane - ethyl acetate - acetic acid 20:10:1. Detection of free-radicals scavenging active compounds by spraying with 0.2 % DPPH• solution in methanol, followed by incubation for 30 min in the dark at room temperature. The antioxidant activity was measured by adding the area of the bright yellow zones and expressing it to gallic acid equivalents (GAEs), using gallic acid (1–15 μg/μL) to construct a calibration curve as the model analyte. Biochemical analysis by dipping into freshly prepared α-amylase solution, followed by incubation at 37 °C for 40 min in a humid chamber. After incubation, the plate was immersed in the substrate solution (2 % starch solution), followed by incubation for another 15 min to allow the enzyme-substrate reaction to occur. Detection by spraying with Gram's iodine solution. By comparing the area of blue bands obtained by samples and standard acarbose the inhibitory activity was measured. Linearity was in the range of 1-7 μg/zone for acarbose and 1-15 μg/zone for gallic acid. The LOD and LOQ were 3 and 9 μg for both acarbose and gallic acid. Further analysis by total reflectance-Fourier-transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy.

Trends Anal. Chem. 157, 116828 (2022). Review of the analysis of drugs of abuse in exhaled breath. The paper described sampling devices, sample pretreatment techniques and the application of chromatographic techniques, including TLC for the analysis of drugs of abuse.

Chinese Medicine 10, 13 (2015). Samples were root and rhizome extracts of Panax notoginseng (Araliaceae), either raw or in the form of commercial granules. Standards were ginsenosides Rg1, Rb1, Rd, Re and Rg2, notoginsenoside NR1. TLC on silica gel with chloroform – ethyl acetate – methanol – water 15:40:22:9, followed by 10 min air drying. Derivatization for ginsenosides by immersion into sulfuric acid (10 % in ice cold methanol), followed by 10 min air drying and 5 min heating at 100 °C. Quantification by densitometric fluorescence measurement (deuterium and tungstene lamp, 366 nm). For each standard the linear range was 0.05-1 mg/mL (LOQ comprised between 38 and 431 µg/µL). As NR1 and Re (ratio ca. 2:1) had almost the same hRF, they were quantified together as one substance. Multivariate analysis through hierarchical (HCA) and principal component analyses (PCA) was used to order the samples into two clusters, according to the analyte concentrations, the raw plant extracts being richer than most of the commercial products. This TLC method was compared to quantification through UPLC-PDA (Ultra-performance liquid chromatography with photo diode array), which was more sensitive (LOQ between 10 and 49 µg/µL) but did not allow the separation between Rg1 and Re (ratio ca. 6:1).

Chinese Medicine 7, 12 (2012). TLC of a Soxhlet hydro-ethanolic extract of Trichosanthes lobata leaves (Cucurbitaceae) on silica gel with n-hexane – ethyl acetate 7:3. Derivatization with anisaldehyde – sulfuric acid reagent. The presence of flavonoids, saponins, and tannins was found.

Chinese Medicine 16, 98 (2021). Preparative TLC on silica gel for the isolation of bisbakuchiol N (a terpenophenolic) from a cyclohexane extract of Psoralea corylifolia (= Cullen corylifolia, Fabaceae) mature fruits, after fractionation on silica gel, cyclodextrane and reverse-phase columns. Mobile phase was petroleum ether – chloroform 10:1. Derivatization with sulfuric acid (10 % in ethanol – water, 19:1).