J. Planar Chromatogr. 35, 313-330 (2022).  HPTLC of orange peel extract on silica gel with gradient multiple development using seven different polarity ranges: cyclohexane, cyclohexane - n-heptane 3:7, cyclohexane - methyl tert-butyl ether 43:7, cyclohexane - methyl tert-butyl ether 7:3, cyclohexane - methyl tert-butyl ether 3:7, methyl tert-butyl ether, methyl acetate - ethanol 9:1, ethyl acetate - ethanol - formic acid 44:5:1. Detection by spraying with vanillin reagent (100 mg vanillin dissolved in 9.8 mL ethanol and 0.2 mL sulfuric acid), followed by heating at 100 °C for 2 min. DPPH staining was performed with 2 mL of a DPPH solution (15 mg dissolved in 10 mL of methanol). Bioautography was performed by dipping into Aliivibrio fischeri bacteria suspension for 6 s, followed by measurement of bioluminescence within 15 min. In this sample, more than 50 compounds could be separated.

J. Planar Chromatogr. 35, 229-241 (2022). Review of the advances, limitations and challenges faced by the application of HPTLC for lipidomic analysis. The paper described methods for the separation of phospholipids (PL) and/or sphingolipids (SL) on silica gel HPTLC plates from different samples in lipidomic studies, including matrices and development conditions. HPTLC methods for separating lipid classes and subclasses, combined with semi-quantification by UV‒FL densitometry and mass spectrometry were also described. HPTLC and genetic knockouts was also discussed as an emerging field. 

J Chromatogr Sci, 60 (9), 832-839 (2022). Establishment of two TLC methods for the synchronous estimation of cinnarizine (Cinn) and acefyline heptaminol (Acef) in the presence of reported Cinn/Acef degradation products, as well as theophylline (Theo) as potential impurity of Acef. TLC on silica gel (1) for Cinn with dichloromethane - methanol - formic acid 30:2:1 and (2) for Acef with the same solvents in ratio 150:7.5:4. Quantitative determination by densitometry at 254 nm showed that Cinn and Acef are well separated from their degradation products. The concentration range was 0.2 - 1.8 and 2 - 18 μg/zone for Cinn and Acef, respectively, with mean percentage recoveries of 99.2 / 99.8 and 99.2 / 99.7 for method 1 and method 2, respectively. The method is selective, robust and retained its accuracy in up to 50 % of Cinn/Acef reported degradation products and Theo. Application of the two methods to a coformulated drug product comprising Cinn and Acef with satisfactory results showing statistically no significant differences compared with those obtained by reference ones.

J Chromatogr Sci, 60 (10), 946 - 952 (2022). Study of the mechanism of micellar thin layer chromatography (MTLC) and development of a new simple and sensitive method for simultaneous separation of empagliflozin, linagliptin and metformin hydrochloride ternary mixture. TLC using a micellar mobile phase composed of methanol and aqueous solution of each of three different surfactants, sodium dodecyl sulphate (SDS), benzalkonium chloride (BAC) and polysorbate 80 (tween 80), in ratio of 2:3. Micellar TLC determination at 237 nm. Investigation of the quantitative structure - retention relationships by modeling, evaluating and validating with a molecular operating environment software. Discussion of the basis for selecting surfactants, for example the separation using SDS (anionic surfactant) and BAC (cationic surfactant) depended on ionization potential (AMI-IP), partition coefficient (logP (o/w)) and hydrogen bond donor atoms (a-don), whereas the separation using tween 80 depended mainly on the lipophilicity (RM0), solvation energy (E-sol) and Van der Waals energy (E-vdw).

Drug Standards of China 22 (3), 259-264 (2021). Gentianella acuta (Michx.) Hulten is a herbal traditional Chinese medicine, containing mainly efficacy components like diphenylpyrione, cycloether terpenoids, flavonoids, and triterpenoids. It has liver protection, hypoglycemic, anti-inflammatory and other pharmacological activities, and is used clinically to treat jaundice, headache, fever, dry mouth and bile fever etc. To establish a quality standard of the herb, TLC was used for the investigation of the chemical composition and fingerprints. TLC of methanolic extracts of 10 batches of Gentianella acuta  collected from different regions (A) for cycloether terpene components (gentiopicroside and swertimarin), on silica gel with ethyl acetate - methanol - water 4:1:1, detection under UV 254 nm, identification by comparison of the fingerprints with those of the standards gentiopicroside and swertimarin; (B) for terpenoids (oleanolic acid), on silica gel with chloroform - methanol - ammonium hydroxide 20:6:1, detection under UV 254 nm, identification by comparison of the fingerprints with those of the oleanolic acid standard; (C) for aqueous extracts (water-soluble components such as flavonoids and phenolic acids), on silica gel with 1-butanol - acetic acid - water 9:3:2, detection by spraying with 5 % aluminium trichloride solution and evaluation under UV 366 nm, identification by comparison of the fingerprints with those of the oleanolic acid standard. The results showed that the TLC profiles of 10 batches were very similar, and well consistent with the HPLC fingerprint results. In addition, gentiopicroside, swertimarin and oleanolic acid were identified by TLC in the medicine, thus can be used as the target components of the identification. Therefore, the results of this study can be used as the basis for the authenticity identification and quality evaluation of the medicine.

J Chromatogr Sci, 60(5), 472-477 (2022). Discussion of the extensive use of reversed phase chromatography in analytical and preparative applications in modern pharmaceutical industry and science, stressing a special place of the normal phase adsorption chromatography in purifying post-reaction mixtures or the separation of natural extracts, especially in wet load mode due to its simplicity and high velocity of preparation. The presented TLC gradient optimization strategy for wet load separations yields repeatable results of separations for different compounds without worrying about negative impact of wet loading on separation quality.The strategy uses an elution model of the desired compound, which is used to develop the gradient method. I also allows to standardize the separation time, because gradient methods performed by the TLC gradient optimization strategy have a similar duration time in column volumes. Therefore the method can simply be scaled using the column volume as a base unit in calculations.

J Chromatogr Sci, 60 (6), 606-612 (2022). Simultaneous determination of sofosbuvir and daclatasvir, co-formulated as directly acting antiviral agents used for treatment of hepatitis C virus, by TLC on silica gel with ethyl acetate - hexane - methanol 18:1:1. Both substances were quantitatively separated in one analytical run. Quantitative determination by densitometry at 280 nm with linearity range of 0.4 - 25.4 μg/band for sofosbuvir and 0.4 - 12.8 μg/band for daclatasvir. The method is time- and cost-saving, which is even more important for some combinations on the market, such as Darvoni® tablets.

J Strait Pharm 33 (8), 46-48 (2021). Yinling Heji is a TCM drug, containing Artemisia capillaris Thunb., Scutellaria L., Radix Rehmanniae Preparata etc. It clears heat and dampness, is mainly used for the prevention and treatment of neonatal jaundice, and has a good effect on children with mild diseases. For quality control, microemulsion thin-layer chromatography on polyamide layer, (A) for Herba Artemisiae Scopariae, of methanol extracts of the test sample (TCM prescription drug), methanol extracts of the test sample without Herba Artemisiae Scopariae, methanolic extracts of Herba Artemisiae Scopariae and standard chlorogenic acid in methanol, (B) for Scutellaria L., methanol extracts of the test sample, methanol extracts of the test sample without Scutellaria L., methanolic extracts of Scutellaria L. and standard baicalin in methanol, (C) for Rhei Radix et Rhizoma, methanol extracts of the test sample, methanol extracts of the test sample without Rhei Radix et Rhizoma, methanolic extracts of Rhei Radix et Rhizoma, and standard emodin in methanol. Development with (sodium dodecyl sulfate - n-butanol - cyclohexane - water 27:63:10:300) - formic acid 9:1.