Chromatographia 68 (9-10), 855-859 (2008). HPTLC of moclobemide on silica gel with benzene – methanol – 40 % ammonia 70:30:1. Quantification by absorbance measurement at 238 nm. The degradation products reached under acidic, basic, and oxidising conditions were well resolved from the pure drug. Linearity was in the range of 50–600 ng/band, with a determination coefficient r2 of 0.9967 ± 0.51. LOD and LOQ, determined experimentally, were 10 and 30 ng/band, respectively. The method was used to investigate the kinetics of alkaline degradation, the Arrhenius plot was constructed and the activation energy calculated.

J. Liq. Chromatogr. Relat. Technol. 31, 1943-1958 (2008). TLC of salicylanilide on silica gel and silica gel mixed with Kieselguhr (with and without brilliant green as a detection reagent) with chloroform in a chamber saturated for 30 min. Detection without a reagent and by treatment with a 50 mg/100mL aqueous solution of brilliant green. Quantitative determination by absorbance measurement at 597, 305, and 268 nm. Proposition of a new index to evaluate objectively the visualizing effects of detected substances on thin layer using a densitometric method. The limit of detection, detection index, broadening index, modified contrast index, densitometric visualizing index, and linearity range were used to evaluate the visualizing effects of salicylanilide.

using HPLC, HPTLC and densitometry. Phytochem. Anal. 19, 550-559 (2008). HPTLC of the leaves of Lawsonia inermis L., on silica gel with ethyl acetate – formic acid – water 82:9:9 followed by drying at 110 °C for 15 min. Detection by spraying with diphenylborinic acid aminoethylester 0.5 % in ethyl acetate, followed by drying and dipping into macrogol reagent (1 g polyethylene glycol 400 in 20 mL dichloromethane). Quantitative determination by absorbance measurement at 337 nm. Chemical fingerprint was used for quality evaluation of herbal products and detection of adulteration. Comparison with an HPLC method gave comparable results.

Chem. 18(1), 667-672 (2006). HPTLC of mefenamic acid and drotaverine HCl in tablets on silica gel with methanol - toluene - triethylamine 10:75:2. Quantitative determination by absorbance measurement at 241 nm. The hRf values were 31 and 47 for mefenamic acid and drotaverine HCl, respectively. The method was validated in terms of accuracy, precision, specificity, ruggedness. Linearity was between 3800 and 8400 ng for mefenamic acid and 1200 and 2700 ng for drotaverine HCl. The recovery (by standard addition method) was in the range of 99.1-100.9 % for both compounds. The method could be used for routine analysis of these compounds and their combined dosage form.

Ind. J. Pharm. Sci. 70(3), 386-390 (2008). HPTLC for the simultaneous estimation of ondansetron combinations in solid dosage form with omeprazole and rabeprazole, on silica gel with dichloromethane - methanol 9:1. Quantitative determination by absorbance measurement at 309 nm for combinations of ondansetron with omeprazole and at 294 nm for ondansetron with rabeprazole. The hRf value of ondansetron and omeprazole was 42 and 54, respectively, while for ondansetron and rabeprazole hRF values were 41 and 51 respectively. Linearity was between 100 and 500 ng/spot for three drugs. The method can be employed for routine quality control of such formulation.

J. Liq. Chromatogr. Relat. Technol. 31, 1892-1902 (2008). HPTLC of hydrochlorothiazide, walsartan, kandesartan, and enalapril on silica gel after chamber saturation using ethyl acetate - tetrahydrofuran - acetic acid 16:4:1 (for kandesartan and walsartan present together with hydrochlorothiazide) and 1-butanol - acetic acid - water 12:3:5 (for enalapril and hydrochlorothiazide). Quantitative determination by absorbance measurement at 252 nm for walsartan and kandesartan, at 274 nm for hydrochlorothiazide and at 208 nm for enalapril. The method was of high sensitivity and specific to analyte constituents.

Phosphorus, Sulfur Silicon Relat. Elem. 184, 1139-1148 (2009). The new TLC system for sulfide ions detection is based on the use of 2,4,6-triphenylpyrylium salts as pre-chromatographic derivatization reagents. The cations L1 (2,4,6-triphenylpyrylium) or LN1 (4-[p-(N,N-dimethylamino) phenyl]-2,6-diphenylpyrylium) were used in the derivatization reactions in a tube or directly on the TLC plate before the developing step. TLC of L1 on silica gel with methanol – dichloromethane 1:5. TLC of LN1 on cellulose with phosphoric buffer (pH 6.0) – acetonitrile – 1,4-dioxane 4:2:1. The detection procedure allows selective and sensitive detection for sulfide anions at several dozen pmol/spot.

Phytochem. Anal. 20, 253-255 (2009). HPTLC of saponins in the tea seed meal of Camellia oleifera on silica gel with ethyl acetate – methanol – water 4:2:1. Quantitative determination by absorbance measurement at 214 nm. The hRf value of tea saponin was 40 and selectivity regarding matrix was given. The correlation coefficient was 0.9978 and the relative standard deviation 1.6 %. Linearity was between 0.9 and 22.2 µg/spot. The limit of detection and quantification was 870 ng and 2900 ng/spot, respectively.