J. AOAC Int. 88, 1517-1524 (2005). HPTLC of fenofibrate and gemfibrozil on diol phases in horizontal chambers using the sandwich technique with hexane - tetrahydrofuran 4:1. Quantitative determination by classical densitometry at 227 nm and videodensitometry at 254 nm. Recovery in the densitometric assay was 101.4 % for fenofibrate and 100.5 % for gemfibrozil. Videodensitometry resulted in recoveries of 102.7 % and 98.8 %, respectively.

J. Planar Chromatogr. 18, 460-464 (2005). HPTLC of ethamsylate and mefenamic acid on silica gel prewashed with methanol, in a pre-saturated twin-trough chamber with chloroform - methanol - acetic acid 50:40:1. After drying at 50 °C for 5 min quantitative determination by absorbance measurement at 300 nm. The validated calibration range was 500-2500 ng/spot (r = 0.998) and 500-2500 ng/spot (r = 0.997) for ethamsylate and mefenamic acid, respectively.

J. Liq. Chrom. & Rel. Technol. 26, 3453-3462 (2003). HPTLC of caffeine and acetaminophen on silica gel in a saturated twin-trough chamber with ethyl acetate - glacial acetic acid 19:1. Quantification at 254 nm. Diphenhydramine, pseudoephedrine, and acetaminophen were well separated from the caffeine zone. Precision (relative standard deviation) was 1.19 %; limit of detection was 0.2 µg for caffeine and 0.08 µg for acetaminophen; precision of duplicate samples (RSD) ranged from 0.95 to 7.56 %.

Indian J. Pharm Sciences 67 (6), 762-764 (2005). HPTLC of fenofibrate in methanolic capsule extracts on silica gel with toluene - chloroform 7:3 with chamber saturation for 10 min. Quantitative determination by absorbance measurement at 296 nm. Linearity range was 1.2-3.8 g with recovery of 101.43 %. The proposed validated method was stability indicating and useful for routine analysis.

Indian Drugs 42 (7), 465-468 (2005). HPTLC of tizanidine and diclofenac in tablet formulations on silica gel with chloroform - methanol 4:1. Quantitative determination by absorbance measurement at 230 nm. Cetrizine was used as an internal standard. The solvent system was found to give compact spots for diclofenac sodium (Rf value 0.86), tizanidine (0.26) and cetrizine (0.52). The method was validated for linearity, accuracy and precision. Linearity for tizanidine was 0.6-1.4 µg/mL, and for diclofenac sodium 7.5-17.5 µg/mL . The mean recoveries obtained for tizanidine and diclofenac sodium were 98.73 % and 99.70 %, respectively. The proposed method was accurate, precise, selective and rapid for simultaneous estimation of tizanidine and diclofenac sodium in tablets.

J. Planar Chromatogr. 19, 401-404 (2006). TLC of methionine, L-cystine, calcium pantothenate, vitamin B1, vitamin B7, and p-aminobenzoic acid on silica gel in a pre-saturated chamber with n-propanol - water - chloroform 5:2:1. Quantification of methionine was based on the oxidation and reaction with leuco xylene cyanol FF solution, which formed a blue dye. Quantitative determination by absorbance measurement at 613 nm.

Acta Chrom. 13, 109-116 (2003). HPTLC of the laxative bisacodyl in enteric-coated tablets on silica gel with concentrating zone and 19 channels, pre-cleaned with dichloromethane – methanol 1:1, with ethyl acetate–methanol–glacial acetic acid 17:2:1. Quantitative determinaion by absorbance measurement at 254 nm. The method was validated and can be used for routine analysis of the pharmaceutical preparation in industry quality control and regulatory laboratories. An alternative extraction procedure and mobile phase are suggested for analysis of bisacodyl tablets with different formulations.

Anal. Bioanal. Chem. 387, 1083-1093 (2007). A new HPTLC method for trace analysis (low µg/kg range) of the five heterocyclic aromatic amines PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine), MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline), norharmane (9H-pyrido[3,4-b]indole) and harmane (1-methyl-9H-pyrido[3,4-b]indole) in meat samples has been established. HPTLC on LiChrospher silica gel WRF with methanol – chloroform 1:9. Using the ADC2, the plate activity was adjusted to 34 % relative air humidity with MgCl2 x 6H2O for 15 min and, at the same time, chamber saturation with 35 mL aqueous ammonia 28 % – ultrapure water 1:4 was performed for 20 min, followed by alkaline plate preconditioning for 15 min. The development was performed in a fresh chamber. Quantitative determination by absorbance measurement at UV 262 nm and 316 nm, and fluorescence measurement at UV 366/>400 nm. The UV wavelength 316 nm was later substituted by 313/>340 nm for a more selective and sensitive determination of PhIP in the meat matrix. Mass spectrometric analysis was performed in ESI+ mode for confirmation of positive findings. The method was validated according to ICH guidelines. Repeatability was better than 3.3 % (n=14), the intermediate precision (n=6, peak area) was 0.4 % (PhIP), 0.6 % (MeIQx), 0.7 % (4,8-DiMeIQx), 0.9 % (norharmane) and 1.1 % (harmane). Reproducibility of the migration distance was better than 1.3 % (n=6). LODs were 4 ng/band for PhIP, 5 ng/band for MeIQx, 4 ng/band for 4,8-DiMeIQx, and 0.4 ng/band each for norharmane and harmane. LOQs were 6 ng/band for PhIP, 14 ng/band for MeIQx, 11 ng/band for 4,8-DiMeIQx, and 0.8 ng/band each for norharmane and harmane. Selectivity in the meat matrix was proven. Confirmation of the substances found in meat was performed by MS. In the working range RSDs of the calibration functions were between 1.9 and 3.6 %.