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. AOAC Int. 91, 1154-1161 (2008). HPTLC of 3 key whithanolides, namely withaferin-A, 12-deoxywithastramonolide, and withanolide-A on silica gel with dichloromethane - methanol - acetone - diethylether 15:1:1:1 in a saturated twin-trough chamber at 25 °C and relative humidity of 35-40 %. Quantitative determination by absorbance measurement at 230 nm. Detection by immersion in freshly prepared vanillin-sulfuric acid reagent for 2 s followed by heating at 110 °C for 10 min.

J. Planar Chromatogr. 22, 97-100 (2009). TLC of (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, theaflavin, theaflavin 3-gallate, theaflavin 3’-gallate, and theaflavin 3,3’-digallate on polyamide phase in a horizontal chamber (saturated for 15 min) by twofold development with chloroform - methanol 2:3 or n-butanol - acetone - acetic acid 5:5:3. Separation of the flavonols myricetin, quercetin, kaempferol, rutin and the phenolic acids gallic acid, chlorogenic acid, and caffeic acid was achieved by twofold development with chloroform - methanol 2:3. Detection by spraying with iron(III) chloride solution and evaluation under daylight. Quantitative determination by absorbance measurement at 600 nm.

Anal. Chim. Acta 577 (1), 46-51 (2006). HPTLC of trigonelline in herbal extracts and in pharmaceutical dosage forms on silica gel with n-propanol - methanol - water 4:1:4. Quantitative determination by absorbance measurement at 269 nm. Linearity was between 100 - 1200 ng/spot (via peak area) and the correlation coefficient was 0.9991. The trigonelline content of herbal extracts quantified and estimated from the formulation was found to be well within limits (± 5 %) of the labeled content of the formulations. The method is reproducible and selective for the estimation of trigonelline by statistical analysis of the data.

J. Planar Chromatogr. 22, 157-161 (2009). Safed musli is the common name for Chlorophytum borivilianum, whereas shatavari is Asparagus racemosus, both of the liliaceae family. HPTLC of saponins and sapogenins on silica gel with chloroform - methanol - water 32:25:5 for saponins and with petroleum ether - ethyl actate 4:1 for sapogenins. Detection of saponins by spraying with anisaldehyde reagent and with Ehrlich’s reagent, followed by densitometric analysis at 620 and 510 nm. Detection of sapogenins by spraying with Liebermann Burchard reagent, followed by densitometric analysis at 580 nm.

Abstract No. 9145, IHCB (2009). Terminalia chebula (an important constituent of Triphala, a popular ayurvedic formulation) was standardized for gallic acid content by HPTLC on silica gel with toluene - ethyl acetate - formic acid 10:10:3. The hRf value of gallic acid was 45. Quantitative determination by absorbance measurement at 254 nm. The method was linear in the range of 150-550 ng/spot. Hydroalcoholic extracts of the fruit pulp contained 10.5 mg/g gallic acid.