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.

Chinese J. Ethnomed. & Ethnopharm. (10), 36-39 (2021). Huangjia Ruangan granules is a TCM preparation, which relaxes the liver and promotes blood circulation, and is used for treating liver fibrosis and early cirrhosis, spleen deficiency, liver depression and blood stasis. (A) Identification of Salvia miltiorrhiza Bge, Pueraria lobata (Willd.) Ohwi, and Paeoniae rubra root, by TLC of the methanol extracts, the control solutions lacking the three drugs, and the standards tanshinone IIA, puerarin, paeoniflorin, on silica gel first with chloroform – methanol – water 70:25:2.5 to 5 cm and then with toluene – ethyl acetate 24:1 to 8 cm; detection by spraying with 5 % vanillin in sulfuric acid – ethanol 1:200 and heating at 105 ˚C until the zones are visible in white light and UV 365 nm. (B) Identification of Astragali Radix, Panax notoginseng (Burkill) F. H. Chen ex C. H.) and Radix Bupleuri, by TLC of the methanol extracts, the control solutions lacking the three drugs and the standards astragaloside lV, notoginsenoside R1 and saikosaponin A, on silica gel with butanol – ethyl acetate – water 4:3:5 to 17 cm, detection by spraying with 2 % ethanol p-dimethylaminobenzaldehyde solution - sulfuric acid 2:3 and heating at 80 ˚C until the zones are visible, evaluation in white light and at UV 365 nm. The method was successfully applyed to identify six major ingredients in Huangjia Ruangan granules on the same plate through multi-information obtained, and proved to be simple, fast, specific, reproducible, robust and well suitable for the purpose.

J. Trad. Chinese Veterinary Med. 55 (1), 15-19 (2021). Qixingcha Keli is a TCM preparation converted from human to animal use, for the treatment of gastric stagnation in piglets and other animals. Quality control of its component (A) Crataegus L. by TLC of the ethanol extracts, the control solutions with and without Crataegus L. on silica gel with ethyl ether - chloroform - formic acid 5:5:1 to 9 cm. Detection by heating the plates at 105 ˚C for 15 min, then spraying with 0.05 % bromophenol solution (pH = 7.5) and viewing in white light. For component (B) Glycyrrhiza uralensis Fisch., TLC of the ethanol extracts, the control solutions with or without Glycyrrhiza uralensis Fisch. on silica gel containing 1 % NaOH with ethyl acetate - formic acid - glacial acetic acid - water 15:1:1:1 to 18 cm, detection by spraying with 10 % sulfuric acid in ethanol and heating at 105 ˚C, evaluation in white light and at UV 365 nm. For (C) Uncaria rhynchophylla (Miq.) Miq. ex Havil., TLC of the ethanol extracts and the control solutions on silica gel with petroleum ether (60-90 ˚C) - propanone 3:2 to 9 cm, detection at UV 254 nm. For (D) Semen Coicis, by TLC of the ethyl acetate extracts and control solutions on silica gel with petroleum ether (60-90 ˚C) - ethyl ether - glacial acetic acid 166:34:1 to 9 cm, detection by spraying with 5 % vanillin in sulfuric acid - ethanol 1:200 and heating at 105 ˚C, detection in white light and at UV 365 nm.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1968429 (2021). Review of bioautography procedures of antimicrobial compounds in plants, including extraction of plant material, stationary and mobile phases in direct bioautography, chemical derivatization and biological detection of bioactive compounds and structure elucidation of bioactive bands. The paper also discussed new aspects of identification of biologically active substances in accordance with the principles of green analytical chemistry, and with special reference to substances with antimicrobial properties.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1939046 (2021). HPTLC of picroside-I (1), andrographolide (2) and silybin (3) in Picrorhiza kurroa (roots), Andrographis paniculata (aerial parts) and Silybum marianum (seeds), respectively, on silica gel with n-butanol - glacial acetic acid - water 6:1:3. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (3) were 49, 68 and 89, respectively. Linearity was between 60 and 600 ng/zone for (1) to (3). The intermediate precision was below 2 %. The LOD and LOQ were 15 and 45 ng/zone for (1), 22 and 67 ng/zone for (2) and 26 and 78 ng/zone for (3), respectively. Recovery was between 99.7 and 103.7 % for (1), 99.7 and 101.1 % for (2) and 99.0 and 101.7 % for (3).

J. Food. Sci. 81, 2218-2223 (2016). HPTLC of Coreopsis tinctoria samples on silica gel with toluene - ethyl acetate - formic acid - water 9:20:6:3. DPPH bioautography assay by spraying with 0.04 % 2,2-diphenyl-1-picrylhydrazyl in methanol under dark conditions. Detection under UV light at 535 nm. The hRF values for the antioxidant compounds were 30 for flavanomarein, 37 for marein and chlorogenic acid, 45 for 5,7,3',5'-tetrahydroxyflavanone-7-O-glucoside, 62 for 3,5-dicaffeoylquinic acid and 76 for isookanin and okanin. 

Sci. Agropecu. 12, 161-168 (2021). HPTLC of annonacin in the leaves of soursop (Annona muricata) and microencapsulated extract on silica gel with chloroform - cyclohexane - diethylamine 2:1:1. Quantitative determination by absorbance measurement at 210 nm. 

Anal. Bioanal. Chem. 412, 6789-3809 (2020). HPTLC of Ginkgo biloba extracts on silica gel with ethyl acetate - acetic acid - formic acid - water 100:11:11:26 (1) or toluene - ethyl acetate - formic acid 7:3:1 (2). Detection under UV light at 366 nm or by spraying with  natural product reagent (NPR) and polyethylene glycol (PEG). The method allowed to distinguish between characteristic and uncharacteristic unfinished product samples based on the presence or absence of bands corresponding to caffeic acid, rutin, hyperoside, chlorogenic acid, and genistein standards.