J. Planar Chromatogr. 4, 246-250 (1991). HPTLC of benzodiazepines, 3,4-methylenedioxyamphetamine, N-methyl-3,4-methylenedioxyamphetamine, N-ethyl-3,4-methylene-dioxyamphetamine) and caffeine on silica. Eluents for benzodiazepines: trichoromethane – acetone 8:2; MDA, MDMA, and MDE were developed with a 25 step AMD gradient employing toluene, 2-propanol, NH3, ether and ethanol; eluent for caffeine was dichloromethane – methanol 9:1. Detection by FTIR scanning.

J. Planar Chromatogr. 6, 228-231 (1993). OPLC of potassium canrenoate, canrenoic acid and canrenone on silica with different mixtures of methanol and 0.01 M phosphate buffer (pH 5.0). Quantification by densitometry at 285 nm.

Indian Drugs 31 (5), 192-196 (1994). HPTLC of propranolol HCl and hydrochlorothiazide in anti-hypertensive and diuretic combination on silica (prewashed with methanol) with benzene - methanol - ethyl acetate - NH3 80:20:10:2. Densitometry at 280 nm with trimethoprim as internal standard. Recovery 97-98%.

J. Planar Chromatogr. 8, 427-429 (1995). HPTLC of naproxen and ibuprofen on silica with ethyl acetate - acetic acid 19:1. Detection by inspection under UV 254 nm; quantification by densitometry at 231 nm. Simple, sensitive, and fast quantitative HPTLC method.

A regression study employing the ladder of power. J. Planar Chromatogr. 9, 126-128 (1996). TLC of diazepam, oxazepam, and chlordiazepoxide on silica with chloroform - methanol 9:1. Quantification by densitometry in the reflectance mode at 254 nm (absorbance).

Proc 9th Internat. Symp. Instr. Chromatog. Interlaken, April 9.-11. 129-146 (1997). In pharmaceutical analysis TLC can be used for identification, purity testing, stability testing, assay and even to study metabolism. For each of these applications examples show how well TLC may perform in the analysis of antibiotics. Comparison with LC is made. Example for identification: separation of (30) cephalosporins on silanized silica with seven different mobile phases, two of which are sufficient for complete identification. Identification of chlorotetracycline, demeclocycline, doxycycline, metacycline, minocycline, oxytetracycline and tetracycline on impregnated with a 100 g/L solution of edetate with a pH of 7.0, 8.0 or 9.0 with dichloromethane - methanol - water 59:35:6. Detection under UV 365 nm. Determination of neomycin C in neomycin on silica with methanol - 20% sodium chloride solution. Visualization by reaction with ninhydrin. Quantification by fluorescence scanning. Purity control and assay of minocycline and determination of erythromycin are also mentioned.

J. Planar Chromatogr. 10, 420-426 (1997). Computer-simulated two-dimensional chromatograms and optimization functions were used for method development. Discussion of 2-D TLC on silica, RP-18, and silica CN with five different solvent systems. The best separation was achieved by 2-D TLC on silica with ethyl acetate - 1-propanol - water - NH3 50:30:1:1 in the first direction after 15 min chamber saturation and with cyclohexane - toluene - triethylamine 7:2:2 in the second direction without chamber saturation. This method was validated. A pharmacopeial identification test by 2-D TLC is presented; it includes a system-suitability test. Separated H1-antihistamines were cetirizine, chlorcyclizine, cinnarizine, cyclizine, etodroxizine, flunarizine, hydroxyzine, and oxatomide. Buclizine and meclozine can be separated on RP-18 with methanol - 3% sodium chloride solution - hydrochloric acid 36% 50:50:1. Detection under UV 254 nm.

J. AOAC Int. 81, 1128 - 1134 (1998). TLC and HPTLC of naphazoline hydrochloride and chlorpheniramine maleate on silica gel with acetone - 25% NH3 9:10 in a presaturated paper-lined tank. After drying detection under UV and quantitation by densitometry at 280 nm for naphazoline hydrochloride and at 262 nm for chlorpheniramine maleate. Linear relationships between concentration and peak area were obtained for the concentration ranges 2 - 10 g/spot and 4 - 10 g/spot for bulk naphazoline hydrochloride and chlorpheniramine maleate, respectively. Mean recoveries were 99.99 ± 0.75% and 99.67 ± 0.73%, respectively.