J. Liq. Chromatogr. Relat. Technol. 43, 233-246 (2020). HPTLC of lutein (1) and lactucaxanthin (2) in three varieties of lettuce (Iceberg, Romania, and green lettuce) on silica gel with heptane - acetone 7:3. The hRF values for (1) and (2) were 44 and 41, respectively.

J. Liq. Chromatogr. Relat. Technol. 43, 351-360 (2020). HPTLC of colchicine (1) and gloriosine (2) in Gloriosa superba on silica gel with chloroform - acetone - di-ethylamine 5:4:1. Quantitative determination by absorbance measurement at 350 nm. The hR_F values for (1) and (2) were 50 and 40, respectively.  The study promotes the use of G. superba as an adjuvant therapy in gouty arthritis and helps explore the elite chemotype(s) with validated pharmacological action to meet out the medicinal and commercial demands.

J. Liq. Chromatogr. Relat. Technol. 43, 388-393 (2020). HPTLC of carpaine in the leaves of Carica papaya on silica gel with chloroform - methanol 7:3. Detection by dipping into Dragendorff’s reagent. Quantitative determination by absorbance measurement at 510 nm. The hR_F value for carpaine was 59. Linearity was between 0.4 and 1.2 µg/zone. Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 11 and 33 ng, respectively. Recovery was 101.6 %.

J. Liq. Chromatogr. Relat. Technol. 43, 300-304 (2020). HPTLC of thymol, carvacrol and linalool in Solidago canadensis on silica gel with n-hexane - acetone 4:1. The method was compared with bilateral band compression (BBC) of the 10 mm wide lanes of HPTLC separation, resulting in more than 6 times increase in peak height and peak area. In BBC a solvent flow perpendicular to the direction of chromatogram development squeezes the chromatographic bands into a smaller area The method improved detection sensitivity of sample components with low abundance.

Planta Medica 84(9/10), 584-593 (2018). A review with 120 references on DESI technique coupled with MS for natural products. Paragraph on sample preparation (9 references) compares analyte desorption surfaces: either directly from the biological sample, or indirectly from surfaces on which the sample had been imprinted. Direct desorption can be performed only from samples with hard, smooth and regular surfaces, or from cryosections, which are usual for animal tissues. For plants, indirect analysis is preferable because of their wax-rich, hydrophobic, absorbent and/or irregular surfaces. Imprinting of plant organs and tissues can be performed either on glass (however with a very rapid ablation of the analytes from its surface), or on sorbent material, like TLC silica gel or porous polytetrafluoroethylene (PTFE). While PTFE layers are reported as more expensive and better in terms of reproducibility and quantitative analysis, both TLC and PTFE layers have similar performance for analyte retention until desorption.

Planta Medica 84(9/10), 710-715 (2018). The fractionation of an n-butanol extract of Cistanche phelypaea (Orobanchaceae) aerial parts through cyclodextran column chromatography with methanol was monitored on TLC silica gel with chloroform – methanol – water 70:30:3, detection by spraying with cerium sulfate reagent. In the 11 major fractions obtained, 4 new phenylethanoid glycosides were further identified, as well as brandioside (a phenylpropanoid glycoside), and heterosides of apigenin (flavonoid) and of pinoresinol (lignan).

Planta Medica 84(9/10), 716-720 (2018). The fractionations of n-hexane and chloroform extracts of Guarea guidonia aerial parts (Meliaceae) through silica gel column chromatography was monitored on TLC silica gel with cerium sulfate / sulfuric acid as derivatization reagent. In the fractions obtained, 3 new tirucallane-type triterpenoids (guareolide, guareoic acids A and B) were further identified, as well as other terpenoids (flindissone, acetyldihydronomilin, picroquassin E, boscartol C, and acneorubins A, B, and X).

Planta Medica 84(9/10), 729-735 (2018). The chloroform fraction of a methanolic extract of Euphorbia taurinensis whole plant (Euphorbiaceae) was submitted to a multi-step fractionation through column chromatography. Monitoring by TLC on silica gel (mobile phases see below) followed by derivatization with concentrated sulfuric acid and heating at 105°C. The fractions obtained were purified by repeated cycles of preparative TLC alone or alternating with preparative HPLC, leading to the isolation of segetane, ingenane, and jatrophane diterpenes. Depending on the subfractions, preparative TLC silica gel and reverse-phase C18 layers were used, with cyclohexane – ethyl acetate – ethanol 25:15:1 for normal phase, and with mixtures of acetonitrile (or methanol) and water for RP.