J. Pharm. Biomed. Anal. 36, 33-41 (2004). A sensitive selective, precise and robust HPTLC method for the analysis of E and Z stereoisomers of guggulsterone (the hypolipidemic agent in the gum-resin exudates of Commiphora mukul) both as a bulk drug and in formulations was developed and validated. Separation on silica gel with toluene - acetone 9:1. Quantitative determination by absorbance measurement at 250 nm. This system was found to give compact spots for E- and Z-guggulsterone (Rf value of 0.38 ± 0.02 and 0.46 ± 0.02 respectively) following double development with the same mobile phase. Both E- and Z-guggulsterone showed good linearity in the concentration range of 100-6000 ng/spot. The method was validated for precision, robustness, recovery, and specificity. The proposed HPTLC method is suitable for the identification and quantitation of these isomers in herbal extracts and pharmaceutical dosage forms.

J. Planar Chromatogr. 17, 438-443 (2004). Proposals for general standardized HPTLC methodology: 1. Plate material (consistent material, prewashing, direction of development, activation of plates, influence of relative humidity). 2. Sample application (precise and accurate volume, solvent, position, spot or bandwise application). 3. Preparation and storage of mobile phases (stability, possible reaction). 4. Development (saturation, use of a twin-trough chamber, influence of the vapor phase, distance, drying). 5. Derivatization (dipping, spraying, heating). 6. Documentation of plates. 7. Labeling (plates, images). 8. Quantitative evaluation 8. Documentation of work.

J. Planar Chromatogr. 17, 388-390 (2004). HPTLC of uroporphyrins I and III, coproporphyrins I and III, and protoporphyrin on silica gel with binary mobile phases prepared by mixing pure esters, ketones, and xylenes with DMSO in proportions from 0 to 100 %. Detection under UV light at 254 nm. The separation of the porphyrins required the presence of DMSO in the mobile phase.

seed and the phoney, Xanthium Spinosam L. seed) (Chinese). Chinese J. Hosp. Pharm. (Zhongguo Yiyuan yaoxue Zazhi) 25 (2), 185-187 (2005). HPTLC on silica gel with n-butanol - glacial acetic acid - water 4:1:5. Detection by exposing to ammonia vapours. Identification by fingerprint technique combined with morphological differentiation and UV spectra comparison.

IPC 56th 2004, Abstract No. GP-3. Simultaneous HPTLC determination of valdecoxib and tizanidine in tablets on silica gel with n-butyl acetate - formic acid - chloroform 7:3:2. Quantitative determination by densitometric scanning at 283 nm. The Rf values of valdecoxib and tizanidine were 0.78 and 0.39 respectively. Linearity range was 200 - 1000 ng/spot and 60 - 300 ng/spot respectively. Mean recovery for both of the compounds was 99.57 – 101.28 %. The method was validated for accuracy, precision, linearity, LOD, and LOQ.

Chromatographia 61 (5-6), 307-309 (2005). Similarities and differences between the retention characteristics of octadecyl silica gel wettable with water used in TLC and RP-18 used in HPLC have been elucidated by use of the linear relationships between log k and RM. The stationary phases compared were investigated with the same mobile phases - binary mixtures of methanol and water, acetonitrile and water, and tetrahydrofuran and water. For these adsorbents of the same type but differing in specific surface area the correlation line was shifted by log (alpha system I / alpha system II). High values of the correlation coefficients obtained over the whole range of mobile phase organic modifier concentration examined indicated that the TLC systems could be used to predict HPLC conditions for flavonoid separation.

J. Planar Chromatogr. 18, 400-402 (2005). HPTLC of beta-carotene on silica gel and RP-18 with preadsorbent sample-application zones (prewashed with dichloromethane - methanol 1:1) with petroleum ether (35-60 °C) - acetonitrile - methanol 1:2:2 or petroleum ether (20-40°C) - acetone 7:3. HPTLC of biliverdin on silica gel with n-butanol - methanol - water 4:2:3. Quantitative determination by absorbance measurement at 628 nm.

Abstract G-28, IPC (2005). HPTLC of rosuvastatin on silica gel with chloroform - methanol - toluene 3:1:1. Quantitative determination by absorbance measurement. The hRf value of rosuvastatin was 53, recovery rate was between 98-102 %, LOD was 8 ng/spot and LOQ 26 ng/spot.