CBS 96, 2-5 (2006). AMD-HPTLC of amitrol in water samples, on LiChrospher silica gel pre-washed by immersion for 8 h in 1 % formic acid in methanol and drying over night in a desiccator. Development with a 18-step gradient from methanol (saturated with ammonia) to tert. butylmethyl ether over 50 mm. Detection by exposure to HCl vapor followed by dipping into a solution of 0.2 g Bratton - Marshall reagent (N-(1-naphtyl)ethylenediaminedihydrochloride) in 100 mL methanol - dichloromethane 1:4. Visual evaluation. Quantitative determination by absorbance measurement at 490 nm. LOD is 1 ng/spot. Linearity is given in the range of 1 - 10 ng amitrol.

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 (9), 592-596 (2005). HPTLC of rutin in Ginkgo biloba from a solid dosage form, on silica gel with n-butanol - n-propanol - chloroform - acetic acid-water 4:1:2:1:1 containing 1 % formic acid. Quantitative determination by absorbance measurement at 254 nm. Rf value of rutin was 0.24. The method was linear in the range of 30-70 ng/µL. No interference was observed from excipients present in solid dosage form.

Acta Chrom. 17, 250-260 (2006). The ChromImage flatbed scanner densitometer with Galaxie-TLC software has been used for the quantification of silica gel HPTLC. The visible mode was evaluated by determination of the recovery of rhodamine B from a four-dye mixture and by determination of the precision of replicate analysis. Determination of caffeine in analgesic tablets and a cola beverage were performed in the fluorescence-quenching mode.

J. Planar Chromatogr.19 , 282-287 (2006). HPTLC of ajmaline, ajmalicine, and reserpine on silica gel, prewashed with methanol, in an unsaturated twin-trough chamber with toluene - methanol 19:6. Detection by dipping in Dragendorff’s reagent. Quantitative determination by absorbance measurement at 520 nm.

J. Chil. Chem. Soc. 48, 71-73 (2003). HPTLC validation of carbamazepine in saliva samples on silica gel previously activated at 130 ºC for 20 min. Development over 5 cm in a saturated chamber with ethyl acetate – toluene – methanol 5:4:1. Detection by dipping in 60 % perchloric acid in ethanol – water 1:1, followed by heating at 120ºC for 7 min. Quantitative determination by fluorescence measurement at 366 nm. Linearity is between 0.5 and 15.0 ng per spot. The detection limit is 0.18 ng and the quantification limit is 0.54 ng. Precision: The analysis shows an intra-assay variation between 5.1 - 7.4 % and an inter-assay variation between 5.6 - 7.4 %. The method allows separation of carbamazepine from its main metabolites 10,11-dihydrocarbamazepine and carbamazepine-10,11-epoxide.

Leg. Med. 8, 184-187 (2006). HPTLC on silica gel of cocaine urine samples submitted to solid phase extraction prior to derivatization (methylation) with diazomethane. For methylation samples were mixed with 100 µL of a solution freshly prepared by distillation of 2.14 g N-methyl-N-nitroso-p-toluenesulfonamide with 10 mL potassium hydroxide 96 % in ethanol and 30 mL ethyl ether, and kept at room temperature for 1 min to convert benzoylecgonine to cocaine. Development over 7 cm in a saturated chamber with ethyl acetate – cyclo hexane – ammonia 250:100:1. Detection by spraying with Dragendorff reagent (10 mL of 40 % m/v potassium iodide in water; 10 mL of 1 N solution of bismuth nitrate in glacial acetic acid; 80 mL of 10 % v/v sulfuric acid water solution; 2 g of resublimed iodine). The technique is capable to discriminate cocaine from interfering substances such as nicotine, caffeine and even cocaethylene in urine samples. The limit of detection was 100 ng of cocaine.

J. Liq. Chromatogr. & Relat. Technol. 30, 557-574 (2007). TLC of trigonelline (3-carboxy-1-methylpyridinium hydrochloride) and degradation products on silica gel with n-propanol - methanol - water 4:1:4 in a twin-trough chamber. Quantitative determination by absorbance measurement at 269 nm.