Chromatographia 59 (1-2), 121-128 (2004). Relationships between Rf values and mobile phase composition have been determined for urea herbicides and fungicides in normal-phase systems (NP) of the type silica-nonpolar or weakly polar diluent (heptane, toluene, diisopropyl ether) – polar modifier (ethyl acetate, tetrahydrofuran, dioxane, ethyl-methyl ketone and 2-propanol). These relationships constitute a retention database which has enabled to choose optimum systems for preliminary fractionation of a multicomponent mixture of pesticides by zonal micropreparative TLC. The mixture was applied from the edge of the layer in the “frontal + elution” mode which increased the separation efficiency because of displacement effects. The separated simpler fractions were applied to a silica plate and rechromatographed. The plate was videoscanned, furnishing a real picture of the plate showing preliminary separation of the simpler pesticide fractions. Complete separation of the fractions was carried out by two-dimensional thin-layer chromatography on plates with chemically bonded-cyanopropyl silica stationary phase using non-aqueous eluent in the first direction and aqueous reversed-phase eluent in the second direction.

J. Chromatogr. A 1045 (1-2), 223-232 (2004). TLC of dansyl derivatives of biogenic amines (agmatine, putrescine, tryptamine, cadaverine, spermidine, histamine, spermine, tyramine and beta-phenylethylamine) with chloroform - diethyl ether - triethylamine 6:4:1, followed by chloroform - triethylamine 6:1. Quantitative determination by fluorescence measurement at 330/>400 nm. Correlation coefficients of linear regressions were higher than 0.99 for all amines, except for agmatine (0.976). Detection limits were 10 ng for tryptamine, tyramine, histamine and ß-phenylethylamine, and 5 ng for the other amines. The overall repeatability of the chromatography was 1.82 % when including agmatine and barely 1.02 % for the other amines. The accuracy ranged from 105.97 % (agmatine) to 49.92 % (tryptamine). This thin-layer chromatography method was found to be an effective and precise analytical procedure to separate and determine biogenic amines. Its main advantages compared to previous procedures are that it uses less harmful solvent (diethyl ether instead of benzene) and can separate a larger group of biogenic amines.

J. Planar Chromatogr. 18, 349-357 (2005). HPTLC of pesticides (prochloraz, chloroxuron, chlorotoluron, metoxuron, chlorbromuron, cyanazine, flamprop-M-isopropyl, prometryn, permethrin, bitertanol, hexazinone, chlorsulfuron, methabenzthiazuron, phenmedipham, metiocarb, dichlofluanid, propachlor, procymidone, terbuthylazine, propyzamide, tri-allate, bifenthrin) on silica gel, RP-18 W, RP-18, and cyano phases in a horizontal chamber. In adsorbent-gradient TLC silica gel plates were used in the first direction with tetrahydrofuran - n-heptane 1:4. After drying, the plates were cut in narrow strips and connected with RP-18 W or cyano plates, the pesticides were transferred to the before mentioned plates with methanol and developed in the second dimension with water - methanol or water - dioxane. Detection under UV light at 254 or 366 nm. Quantitative determination by densitometry at 254 nm.

J. Planar Chromatogr. 18, 326-329 (2005). HPTLC of levonorgestrel on silica gel (prewashed with chloroform - methanol 1:1 and once with the mobile phase, dried and activated at 100 °C for 15 min) with toluene - 2-propanol 9:1 in an automatic multiple development chamber without chamber saturation. Visual examination under UV light at 254 nm; quantitation by densitometry at 250 nm.

Abstract G-29, IPC (2005). HPTLC of valdecoxib in tablets and human plasma on silica gel with methanol - water - chloroform 6:3:1. Celecoxib was used as internal standard. Quantitative determination by absorbance measurement at 254 nm. The compound was extracted from plasma with ethyl acetate showing an extraction yield of 85 %. Linearity was obtained in the range of 25-200 ng/mL, recovery rate was 99.8 % from tablets and 97.2 % from plasma.

leaf powder by high-performance thin-layer chromatography. J. Planar Chromatogr. 18, 305-307 (2005). HPTLC of methanolic extracts of Cinnnamomum tamala leaves and eugenol on silica gel with toluene - ethyl acetate - formic acid 90:10:0.1. Detection and quantitation by densitometry at 280 nm.

J. Planar Chromatogr. 19, 233-237 (2006). OPLC-HPTLC and OPLC-TLC of xylose, fructose, glucose, galactose, sucrose, maltose, and raffinose on silica gel with acetonitrile - water 17:3 (overrun, performed twice, successively). Detection by use of aniline - diphenylamine - phosphoric acid reagent. Densitometric quantitation at 540 nm.

Indian Drugs 42 (8), 511-515 (2005). HPTLC carvedilol in tablets on silica gel with toluene - methanol - ethyl acetate - ammonia 40:10:5:1. Quantitative determination by absorbance measurement at 254 nm. The method was linear in the range of 50-250 µg/µL with recovery of 98.5-100.2 %. Stability was studied during and after development. Accuracy, precision, and specificity of the method were established.