J. Sep. Sci. 44, 3146-3157 (2021). HPTLC of  gallic acid (1), cinnamic acid (2), piperine (3), eugenol (4), and glycyrrhizin (5) in Divya-Swasari-Vati on silica gel with ethyl acetate - toluene - formic acid 10:9:1 for (1) to (4) and ethyl acetate - formic acid - acetic acid - water 100:10:10:23 for (5). Quantitative determination by absorbance measurement at 280 nm for (1), (2) and (4), 343 nm for (3) and 254 nm for (5). The hRF values for (1) to (5) were 31, 64, 53, 70 and 29, respectively. Linearity was between 400 and 800 µg/mL for (1), 5 and 25 µg/mL for (2), 600 and 1400 µg/mL for (3), 400 and 1200 µg/mL for (4) and 100 and 800 µg/mL for (5). Intermediate precision was below 2 % (n=18). The LOD and LOQ were 180 and 560 ng/g for (1), 3 and 10 ng/g for (2), 8 and 26 µg/g for (3), 3 and 11 µg/g for (4) and 300 and 920 ng/g for (5), respectively. Mean recovery was 96.0 % for (1), 92.3 % for (2), 94.2 % for (3), 96.2 % for (4) and 94.6 % for (5). 

J. Ethnopharmacol. 270, 113842 (2021). HPTLC of diosgenin in the rhizomes of Paris polyphylla on silica gel with toluene - ethyl acetate 7:3. Detection by spraying with anisaldehyde sulphuric acid reagent, followed by heating at 105 °C for 5 min. Quantitative determination by absorbance measurement at 430 nm. The hRF value of diosgenin was 53.

J. Ethnopharmacol. 280, 114417 (2021). HPTLC of bergenin (1), epicatechin (2) and gallic acid (3) in the rhizomes of Bergenia ciliata on silica gel with toluene - ethyl acetate - formic acid 3:7:1. Quantitative determination by absorbance measurement at 280 nm. The hRF values of (1) to (3) were 32, 52 and 74, respectively.

Phytochem. Anal. 3093 (2021). HPTLC of hyperforin (1), hypericin (2) and hyperoside (3) in Hypericum species on silica gel with n-hexane - ethyl acetate 4:1 for (1), toluene - chloroform - ethyl acetate - formic acid 80:50:35:6 for (2) and ethyl acetate - formic acid - acetic acid - water 15:2:2:1 for (3). Detection by spraying with a derivatizing reagent (20 mL of sulfuric acid were carefully added to 120 mL methanol and diluted with 200 mL methanol), followed by heating. Quantitative determination by absorbance measurement at 366 nm. The hRF values of (1) to (3) were 49, 35 ad 49, respectively. Linearity was between 0.4 and 1.4 µg/zone for (1), 20 and 100 ng/zone for (2) and 10 and 100 ng /zone for (3). The intermediate precision was below 2 % (n=6) for (1) to (3). The LOD and LOQ were 120 and 400 ng/zone for (1), 6 and 20 ng/zone for (2) and 3 and 10 ng/zone for (3), respectively. Recovery was between 101.0 and 101.2 % for (1), 98.8 and 100.1 % for (2) and 100.4 and 101.4 % for (3).

Phytochem. Anal. 3091 (2021). Comprehensive review of the application of chromatographic methods for the quality control of fenugreek seeds. The document described systems for the analysis of fenugreek, including the determination of trigonelline, 4-hydroxyisoleucine and diosgenin in seeds from different origins and in herbal formulations.

Phytochem. Anal. 3078 (2021). HPTLC of thymoquinone on silica gel with cyclohexane - ethyl acetate 9:1 (1) and on RP with ethanol - water 4:1 (2). Quantitative determination by absorbance measurement at 259 nm. The hRF value of thymoquinone was 42 for system 1 and 51 for system 2. Linearity was between 25 and 1000 ng/zone for (1) and 50 and 600 ng/zone for (2). The intermediate precision was below 1 % (n=6) for (1) and (2). The LOD and LOQ were 8 and 25 ng/zone for (1) and 17 and 50 ng/zone for (2), respectively. Recovery rate was between 99.0 % and 100.9 % for (1) and 98.4 % and 101.2 % for (2). Analytical GREEnness (AGREE) scores for the systems were predicted using the AGREE software according to the 12 principles of green analytical chemistry.

Phytochem. Anal. 33, 115-126 (2022). HPTLC bioautography of 14 Egyptian plants on silica gel with methylene chloride - methanol 9:1 (system I) or ethyl acetate - methanol - water - glacial acetic acid 120:20:16:1 (system II). Detection by spraying with anisaldehyde/sulfuric acid reagent. Aromatase inhibitory assay was performed by dipping into 112.5 mL cofactor solution (containing 4.5 mL of 0.5 % sodium phosphate buffer, 4.5 mL NADPH regenerating system solution A and 0.9 mL NADPH regenerating system solution B and then completed to volume with distilled water), followed by incubation at 37 °C for half an hour, then re-immersed in 75 mL aromatase E/S mix (containing 120 μL aromatase enzyme, 0.03 mL DBF and 3 mL albumin dissolved in 0.075 M potassium phosphate buffer) and re-incubated for another half an hour. Enzymatic reaction was terminated by immersing plates into 2N sodium hydroxide stop solution. Active zones were observed under UV 366 nm. Calculation of the inhibition zones was performed by reciprocal iso-inhibition volume (RIV) that is based on measuring the zone pixel intensity. The hRF values for chrysin were 63 and 91 in systems I and II, respectivley. The intermediate precision was below 3 % (n=3). Linearity was between 0.1 and 0.3 μg/zone. LOD and LOQ were 80 and 206 ng/zone, respectively. Recovery was between 92.5 and 106.5 %. Two quantification methods, the peak area and RIV method were compared and the RIV method showed superiority over the peak area method with %RSD values of 0.98 and 1.49 compared with 2.86 and 3.58, respectively.

J. Spectroscopy & Spectral Anal. 41 (2), 388-394 (2021). SERS, as a fast and sensitive analytical technology, is widely employed in the fields of analytical chemistry, environmental detection and food safety. However, the real-life samples are mostly mixtures, and an accurate determination of the analytes in complex samples cannot be performed directly by using SERS. TLC as a separation technique is easy to operate, low cost, fast and high-throughput, and has been widely used in the fields of synthetic chemistry, analytical chemistry, medicinal chemistry, and food science. Further, the zones isolated by TLC are first visualized using iodine vapor coloring or fluorescence, and then combined with SERS for efficient qualification and quantitation of the zones of interest. Therefore, the technology of TLC combined with SERS (TLC/SERS) suits rightly for determination of various kinds of complex samples. Moreover, due to the small sample size and the relatively simplicity of the experimental equipment used, it is also suitable for the rapid field screening and detection of relatively complex samples. Introduction of the enhancement mechanism of SERS and the preparation of the active substrate, and demonstration of the broad prospects of TLC/SERS application in the fields of environmental pollutant analysis, food safety monitoring, traditional Chinese medicine and biomedicine identification etc by providing a set of successful application examples.