Abstract G-26, IPC (2005). A simple HPTLC method is reported for analysis of guggulsterones E and Z in herbal extract and market formulations containing commiphora mukul. Guggulsterones were extracted from crude extract and formulations by ethyl acetate. HPTLC on silica gel with n-hexane - ethylacetate 3:1. Quantitative determination by absorbance measurement at 250 nm. The hRf value of E-guggulsterone was 38 and of Z-guggulsterone 46, linearity range for both isomers was 200-5000 ng/mL. The method was validated as per ICH guidelines.

J. AOAC Int. 88, 70-79 (2005). HPTLC of haloperidol, amitriptyline, sulpiride, promazine, fluphenazine, doxepin, diazepam, trifluoperazine, clonazepam, and chlorpromazine in 25 selected psychotropic drugs on silica gel with 30 mobile phases, eight of them were selected based on spot location and developing time. Identification and quantification were carried out based on UV densitometric measurements. In addition to retention factors, the absorption spectra recorded directly from chromatograms were also used in qualitative analysis. Limit of detection ranged from 0.009 to 0.260 µg depending on the wavelength used. A satisfying recovery, ranging from 92.9 to 104.7 %, was achieved for individual constituents.

J. Planar Chromatogr. 18, 336-343 (2005). HPTLC of thirty-three compounds with benzodiazepine properties on silica gel after prewashing first with methanol and then with dichloromethane - methanol 19:1 in a saturated horizontal chamber and three optimized mobile phases: dichloromethane - methanol 19:1, ethyl acetate - cyclohexane - 25 % ammonia 50:40:0.1, and in a third run cyclohexane - acetone - methyl t-butyl ether 3:2:1. Diode-array HPTLC makes it possible to identify all the compounds with high certainty down to a level of 20 ng. An algorithm for spectral recognition which is combined with Rf values from the three separation steps into one fit factor is presented. This set of data is unique for each of the compounds investigated and enables unequivocal identification.

J. Planar Chromatogr. 19, 4-9 (2006). TLC and HPTLC of 2-thioguanidine and 6-mercaptopurine on silica gel with methanol in a horizontal DS-chamber. Spots were visualized with a freshly prepared solution of sodium azide and starch, adjusted to a pH within the range 5.5-6.0, and then exposed to iodine vapor. The thiols became visible as white spots on a violet-gray background. The iodine-azide reagent enabled detection of quantities in the range 1-80 pmol per spot.

Indian Drugs 42 (10), 650-653 (2005). A simple rapid, precise and cost-effective HPTLC method has been developed for the determination of ursolic acid in Oscimum sanctum (Tulsi) leaves and its formulations (Tulsi ghan tablets and Tulsi capsules). HPTLC on silica gel with toluene - ethyl acetate - acetic acid 30:3:1. Detection with anisaldehyde in sulphuric acid reagent followed by heating in an oven at 110 °C. Quantitative determination by absorbance measurement at 580 nm. Linearity of the detector response was given in the range of 40 - 280 ng. LOD was 8 ng. The correlation coefficient obtained from linearity was 0.9985. The standard error was 26.511. The mean assay values of ursolic acid wa found to be 3.485 mg/g, 0.553 mg/g and 3.221 mg/g in tulsi ghan tablets, tulsi capsule and tulsi leaves respectively.

Abstract GP-75, IPC (2005). HPTLC of satranidazole and its degradation products on silica gel with toluene - acetonitrile 3:2. For stability studies, the sample was treated with NaOH, HCl, H2O2 and photolysis. Degradation products were well resolved with significant different Rf values. The method had a linearity range of 100-500 ng. The proposed method suitable to investigate the kinetics of hydrolysis and photodegradation processes with first order in NaOH, and zero order for photolysis.

Indian Drugs 42 (9), 600-603 (2005). HPTLC of cinnarizine and domperidone in tablets, on silica gel with toluene - ethyl acetate - methanol 14:1:5. Quantitative determination by absorbance measurement at 271 nm. Rf values of cinnarizine was 0.85 and of domperidone 0.4. Linearity was observed in the range of 0.1-0.4 for cinnarizine and 0.075-0.3 µg/µL for domperidone. The recoveries were in the range of 98.95-100.25 %. The tablet matrix did not interfere with the assay.

Application of SFC in implementation of uniform design for herbal drug standardization, with thermodynamic study. Acta Chrom. 17, 125-150 (2006). HPTLC of bacoside A3 and bacopaside II on RP-18 F254 after pre-washing with methanol and heating at 60° C for 5 min. Development with toluene – methanol – ethyl acetate 15:5:4 in the dark in a controlled humidity chamber (humidity of 55 - 65 %). Densitometry at 344 nm. The method is available for content determination of bacoside A3 and bacopaside II in herbal extracts and commercial formulations.