Influence of sample preparation methods and conditions. J. Liq. Chrom. & Rel. Technol. 27, 2463-2470 (2004). TLC of 1-(3,4-methylenedioxyphenyl)-2-nitropropene, an intermediate product of MDMA (3,4-(methylenedioxy)methamphetamine, also known as ,ecstasy’, and impurities on silica gel in a horizontal chamber with chloroform - ethyl acetate 49:1. Detection of separated impurities under UV light at 254 and 366 nm.

Indian J. Pharm. Sci. 67 (2), 182-186 (2005). HPTLC of atorvastatin calcium in its commercial single component tablet formulations (10 mg/tablet), on silica gel with benzene-methanol 7:3. The Rf value was 0.46. Quantitative determination by absorbance measurement at 281 nm. The method was validated in terms of linearity (200-600 ng/spot), precision (intraday variation: 0.25 - 1.01 %, interday variation: 0.21 - 0.88 %), accuracy and specificity. The LOD for atorvastatin calcium was 40 ng/spot, the LOQ was 200 ng/spot. The proposed method was successfully applied to determine atorvastatin calcium content of 10 individual tablet units of two market formulations after extracting atorvastatin calcium with methanol. All formulations were compliant with USP specifications (RSD less than or equal to 6 %) of the content uniformity test. The proposed HPTLC method can analyse ten or more formulation units simultaneously on a single plate and provides a faster and cost effective quality control tool for routine analysis of atorvastatin calcium formulation.

J. Planar Chromatogr. 19, 454-462 (2006). HPTLC of enrofloxazine, norfloxazine, oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine, and penicillin G/procaine on cyano phase with 0.05 M oxalic acid - methanol 81:19. Evaluation under UV light at 254 and 366 nm. Quantitative determination of TMP by absorbance measurement at 254 nm, and fluorescence measurement at 366 nm for the other compounds. The SPE-TLC determination was validated for linearity, precision, quantification, and detection limit.

J. Liq. Chromatogr. Relat. Technol. 28, 2195-2209 (2005). HPTLC of 5’-carbamates of zidovudine (3’-azido-3’-deoxythymidine) and thymidine on RP-18 with methanol - buffer pH 7.4 mixtures with methanol contents between 30 and 80 %; or acetone - buffer mixtures with modifier contents between 20 and 80 % in 5 or 10 % increments. Detection after drying at 40°C developed under UV radiation.

J. Liq. Chromatogr. Relat. Technol. 29, 2019-2033 (2006). HPTLC of twelve 3,5-dioxo-4-azatricyclo[5.2.2.02,6]undecanes on RP-18 W and RP-18 in horizontal chambers. Mobile phases were prepared by mixing the respective amounts of water and polar modifiers (methanol, dioxane, acetone) in the range from 50 - 75 or 90 % for RP, and 40, 50 - 65, or 75 % for RP W-plates. Evaluation under UV 254 nm.

J. Liq. Chromatogr. Relat. Technol. 29, 2071-2082 (2006). TLC of S-(+)-naproxen on silica gel (prewashed with methanol - water 9:1 and impregnated with a 0.03 mol/L solution of L-arginine in methanol by dipping for 2 s at 22 +/- 2 °C) with acetonitrile - methanol - water 5:1:1.5 containing several drops of acetic acid to fix the pH at 4.8; and two-dimensional development with acetontrile - methanol - water 10:2:3. Densitometric evaluation at 235 nm.

J. of China Pharm. 23 (20), 38-40 (2014). Nicotine is a toxic substance in tobacco. Studies have shown that nicotine may prevent and treat Alzheimer's disease (AD) and Parkinson's syndrome (PD). At present, the most effective method to treat AD is by inhibiting the activity of acetylcholinesterase (AChE), thus enhancing the cholinergic activity indirectly. In order to clarify the mechanism of nicotine reducing the incidence of AD, the activity of natural AChE inhibitors in Xinjiang Mohe tobacco was screened by TLC on silica gel with (A) ethyl acetate – methanol – ammonium hydroxide 70:30:1, followed by detection via enzyme inhibition (this is not bioautography, as stated in the title): firstly by spraying with 1.0 U/mL AChE (AChE 500 U + tris-HCl buffer solution of pH 7.8 500 mL + bovine serum albumin 500 mg), followed with 1.5 g/L alpha-naphthyl acetate (150 mg in ethanol 40 mL + water 60 mL) and then with 0.5 g/L Fast blue B salt, resulting in white zones on purple background; (B) toluene – ethyl acetate - diethylamine 7:2:1, detection by spraying with 0.2 mmol/L 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical reagent, resulting in white to yellow zones on pale purple background. The results indicated that nicotine in Xinjiang Mohe tobacco could bind to AChE and thus inhibit its activity.

GIT Fachz. Lab. 12, 1221-1223 (1986). Neue wasserbenetzbare HPTLC RP-18 Fertigplatten. New HPTLC RP-18 pre-coated plates wettable by water.) Description of a new HPTLC precoated plate based on silica gel with a reduced degree of modification with octadecyl groups. This plate material is fully wettable with methanol - water mixtures between 0:100 and 100:0. Running times for 50 mm are between 14 and 40 minutes, whereby the maximum running times occur with the 50:50 mixture. Separations of nicotinic acid - isonicotinic acid, of analgesics and of alkaloids.