Chinese J. Pharm. Anal. 28 (9), 1554-1556 (2008). TLC of scalreol on silica gel with n-hexane – ethyl acetate – formic acid 32:16:1. Detection by spraying with vanillin – sulfuric acid – ethanol 1:1:18. Quantification by densitometry at 520 nm. Linearity was between 10 and 50 µg/zone with a determination coefficient of 0.9994. Recovery was 100.1 % (n = 6, %RSD = 0.9). Repeatability (%RSD, n = 6) was 2.1 % within plate and 2.3 % plate-to-plate.

J. Planar Chromatogr. 22, 249-253 (2009). Investigation of the chromatographic behavor of twelve neutral, mixed cobalt(III)complexes of the uns-cis-edda-type in six planar chromatographic systems. Four different stationary phases - silica gel, cyano phase, cellulose, and alumina - were combined with water-organic solvent (methanol or acetone) binary mobile phases. Hydrophilic-interaction chromatography was assumed to be the mechanism determining separation under normal-phase conditions (use of mobile phases with small amounts of water), whereas the use of mobile phases with high water content lead to reversed-phase chromatography.

J. Planar Chromatogr. 23, 14-17 (2010). TLC of vitamin C of different concentrations (0.45, 0.50, 0.55, 0.60, and 0.65 mg/mL) and juice (e. g. orange with grapefruit, orange with apple and carrot, “multi-fruit”) mixed with a methanolic solution of DPPH radical (2,2-diphenyl-1-picrylhydrazyl) on silica gel. Images of plates were evaluated using a specific computer software. The equivalence of the results obtained using the procedure described was demonstrated by applying the traditional UV-visible spectrophotometry.

J. Planar Chromatogr. 23, 7-13 (2010). TLC of the enantiomers of racemic atenolol, metoprolol, propanolol, and labetalol on silica gel using vancomycin as chiral impregnating agent or as chiral phase additive. With vancomycin as impregnating agent, resolution of the enantiomers of atenolol, metoprolol, propanolol, and labetalol was achieved with acetonitrile - methanol - water - dichloromethane 7:1:1:1, acetonitrile - methanol - water 6:1:1, acetonitrile - methanol - water - dichloromethane - glacial acetic acid 14:2:2:2:1, and acetonitrile - methanol - water 15:1:1. With vancomycin as mobile phase additive, resolution of the enantiomers of metoprolol, propanolol, and labetalol was achieved using acetonitrile - methanol - 0.56 mM aqueous vancomycin (pH 5.5) 15:1:2, and acetonitrile - methanol - 0.56 mM aqueous vancomycin (pH 5.5) - dichloromethane 18:2:3:2, respectively. Chromatograms were developed in glass chambers previously equilibrated with the mobile phase at 16 +/- 2 °C for 10-15 min. Detection by exposure to iodine vapor. The detection limits were 1.3, 1.2, 1.5. and 1.4 µg for each enantiomer of atenolol, metoprolol, propanolol, and labetalol, respectively.

International Journal of Green Pharmacy 3 (1), 47-17 (2009). HPTLC of caffeine on silica gel with ethyl acetate - methanol 9:1. Densitometric quantification at 274 nm. The method was linear in the range of 2-14 µg/band. The sample extracted with 5 % diethyl amine in water gave the maximum yield of caffeine (2.1 %). The proposed chromatography gave the best resolution with caffeine at an hRf value of 40. The method can be used for quality control of tea samples in respect of caffeine contents.

J. Serb. Chem. Soc. 74(6), 677-688 (2009). An NP-TLC method has been reported to study the lipophilicity of 5 ACE inhibitors (lisinopril, quinapril, fosinopril, enalapril, cilazapril and their metabolites). TLC on silica gel with several non-aqueous mono and binary solvent systems. Binary mobile phases demonstrated a decrease in hRf values of all 5 ACE inhibitors, i.e. increased retention with increased amounts of the less polar component in the mobile phase. Metabolites usually exhibited stronger retention, i.e. lower hRf values than the corresponding ACE inhibitor. This is probably due to a different interaction with silica gel because of two carboxylic groups in the structure of the metabolites, whereas ACE inhibitors contain only one carboxyclic group. Results obtained on NP-TLC were compared with those by RP-TLC and no significant difference was found regarding lipophilicity.

J. Chromatogr. A 1218 (19), 2793-2811 (2011). A review on the forensic examination of writing ink on documents. The focus in ink analysis is on screening questioned samples and on verifying their compounds in relation to control ink samples. Description of a project designed to develop improved standardization procedures to ensure the best possible reproducibility between analyses run on different HPTLC plates. HPTLC of ink samples (punched from written documents and extracted with tetrahydrofuran – water 4:1) on silica gel with n-butanol – ethanol – water 10:2:3 without chamber saturation. Detection by densitometric measurement of absorption intensities of each point of the elution track directly at 31 wavelengths between 200 and 700 nm.

Microbiol. Res. 166, 255-267 (2011). TLC of lipopeptides (produced by Pseudomonas species in cultures of Pleurotus ostreatus; Pseudomonas reactans was used as a reference) on silica gel with chloroform – methanol – ammonia 80:25:4. Detection by spraying with 0.1 % bromothymol blue in ethanol, followed by heating.