CBS 101, 12-13 (2008). During a drug substance stability study a mass imbalance was discovered in light degraded samples. HPTLC on silica gel first with ethyl acetate - heptane, then, after drying, with tetrahydrofuran in a horizontal developing chamber. Detection under UV 254 nm and by densitometry at 240 nm. During another project differences in color between batches of a drug substance were observed. HPTLC on amino phase with methanol in a horizontal developing chamber. Detection under white light and under UV 366/>400 nm.

J. Planar Chromatogr. 21, 77-82 (2008). Ozone can be detected indirectly in TLC or OPLC zones by use of the bioautographic BioArena system and ozone-eliminating molecules (e.g. d-limonene and indigo carmine) in the culture medium. TLC and OPLC of test substances (trans-resveratrol, aflatoxin B1) on silica gel with a variety of mobile phases (e. g. chloroform - methanol 10:1). The developed and dried TLC plates were immersed in a bacterial suspension of Pseudomonas savastanoi for 20 s. Visualization of the chromatograms with MTT was performed either after a a short draining period or after overnight incubation.

Anal. Chem. 80, 1835-1846 (2008). HPTLC of neutral glycosphingolipids on silica gel with chloroform - methanol - water 120:70:17 and 120:85:20, both supplemented with 2 mM calciumchloride solution. Detection by treatment with orcinol. Quantitative determination by absorbance measurement at 544 nm (orcinol) and 630 nm (indolylphosphate). A TLC overlay assay was performed, the TLC immunodetection procedure used glycosphingolipid antibodies and toxins in conjunction with antitoxin antibodies.

J. Planar Chromatogr. 22, 133-135 (2009). HPTLC of monocrotophos on silica gel with chloroform - acetone 7:3 with chamber saturation. Detection by spraying with 20 % sodium carbonate followed by acidic methanolic iron chloride reagent. Evaluation of purple spots, while organophosphorus, organochlorine, carbamate, and pyrethroid insecticides were not detected as purple spots. Alkaline hydrolysis of monocrotophos yields one molecule each of O,O-dimethylphosphoric acid and N-methylacetoacetamide. After acidiification N-methylacetoacetamide yields the enol form of monomethylamide which reacts with ferric ions to a purple complex. The detection limit for monocrotophos is 0.5 µg/zone.

Anal. Chim. Acta 599 (2), 302-309 (2007). HPTLC of minocycline on silica gel (impregnated with a 10 % (w/v) solution of disodium ethylene diaminetetraacetic acid (EDTA) with a pH of 9.0) with methanol - acetonitrile - isopropyl alcohol - water 10:8:1:1. Quantitative determination by absorbance measurement at 345 nm. The limit of detection was 3.7 ng/spot, recovery was 99.2 - 100.2 %, and precision was good with a %RSD of 0.4 %. The method was able to separate all degradation products (produced by acidic and basic degradation, oxidation and photodegradation) from the pure drug.

J. Chromatogr. B 848 (2), 232-238 (2007). HPTLC of boswellic acids in Boswellia serrata extract and 11-keto-beta-boswellic acid in human plasma on silica gel with hexane - chloroform - methanol 10:10:1. Quantitative determination by absorbance measurement at 260 nm. The linearity range for 11-keto-beta-boswellic acid spiked in 1 mL of plasma was 29 - 146 ng/spot, with a recovery of 91.7 %. The limit of detection and quantification for 11-keto-beta-boswellic acid in human plasma was 9 and 29 ng/mL, respectively. The method was applied for the determination of 11-keto-beta-boswellic acid plasma levels in a clinical pilot study.

J. Planar Chromatogr. 21, 349-353 (2008) TLC of S-(+)-ketoprofen on silica gel (prewashed by development with methanol - water 9:1 and impregnated by dipping for 2 s in a solution of L-arginine in methanol) at 22 +/- 2 °C with acetonitrile - water 5:1 acidified with several drops of glacial acetic acid (to maintain the pH <4.8) in one-dimensional and two-dimensional modes. Quantitative determination by absorbance measurement at 252 nm.

Pharmazie 64, 415-416 (2009). TLC of the pyrrolizidine alkaloid lycopsamine and the guaianolide cumambrin B on silica gel with dichloromethane - methanol - 25 % ammonia 85:14:1. Detection see A. R. Mattocks, Detection of pyrrolizidine alkaloids on thin-layer chromatograms, J. Chromatogr. 27, 505-508 (1967).