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.

J. Planar Chromatogr. 12, 272-274 (1999). HPTLC of cinnarizine (1-benzhydryl-4-cinnamylpiperazine) and domperidone maleate (5-chloro-1-{1-[3-2(2,3-dihydro-2-oxo-1H-benzimidazol-1-yl)propyl]-4-piperidyl}-1,3-dihydrobenzimidazol-2-one.hydrogen-(B)-butendioate.cinnarizine) on silica gel with methanol - dichloromethane - formic acid 25:225:1. Quantitation by densitometry at 276 nm. New simple, rapid and precise TLC method.

Sz. Nyiredy, A. Kakuk (eds.): Planar Chromatography 2000, Lillafüred, Hungary, 24-26 June 2000, Res. Inst. for Med. Plants, p. 143-148. Validated methods: HPTLC of dexamethasone sodium phosphate and neomycin sulfate on silica gel with concentration zone with chloroform - 1-propanol - NH3 1:3:2. HPTLC of ketoconazole on silica gel with n-hexane - acetone 4:1. HPTLC of coenzyme Q10 on silica gel with n-hexane - chloroform - methanol 5:4:1. Quantitation by polynomial regression at 246 nm for dexamethasone sodium phosphate, at 230 nm for ketoconazole, at 275 nm for coenzyme Q10 and after derivatization with ninhydrin solution at 500 nm for neomycin. Precision is found to be between 0,8-2,68 %.

J. Planar Chromatogr. 13, 187-190 (2000). RPTLC of eleven derivatives of 1-[2-hydroxy or 1-[2-acetoxy-3-(4-aryl-1-piperazinyl)propyl]pyrrolidin-2-one on RP 18 with mixtures of acetone - methanol - water, with acetone content between 21.4 and 78.5 %, in 7.1 % increments, and methanol content 14.3 %. Detection under UV.

J. Planar Chromatogr. 14, 188-190 (2001). TLC of finasteride and loratadine on silica gel plates (prewashed with methanol) with chloroform - ethyl acetate 3:2. Evaluation by densitometry at 228 nm. The linear range of the analysis was 0.2 - 2.0 µg, recovery 101.28%. New simple, precise, rapid, selective TLC method.