Anal. Chim. Acta 255, 297-303 (1991). Description of a fiber-optic-based fluorescence instrument for in-situ quantitative scanning in TLC. TLC of phenothiazines on silica with chloroform - methanol 9:1. Enhancing the fluorescence signal by immersion in a mixture of Triton X-100 - chloroform 1:4. Detection limit 5.3 µM for acepromazine and 6.4 µM for propiomazine.

Phytochemica Analysis 3, 160-164 (1992). TLC of norsesquiterpenes of bracken fern extracts on silica with dichloromethane - acetone 3:7. Detection under UV. Isolation of pterosin B by prep. TLC with the conditions indicated above. Elution of the compound from the plate with ethyl acetate. See also M. Saito et al., Phytochemistry 28, 1605-1611 (1989).

J. Trad. Chin. Med. (Zhongguo Zhongyao Zazhi) 16, 741-742 (1991). TLC of phospholipids on silica with chloroform - methanol - acetic acid - ethanol - water 50:8:12:2:1. Detection by spraying with ammonium molybdate reagent. Quantification by densitometry at 700 nm.

J. Planar Chromatogr. 4, 413-415 (1991). HPTLC of diazepam, nordiazepam, ACMP, and MACB on silica with chloroform - ethyl acetate 3:1. Quantification by densitometry (absorbance at 354 nm). Plates were prewashed with chloroform - ethyl acetate 3:1 and aqueous NH3 - methanol 1:9, dried and activated for 15 min at 160°C in order to achieve uniform and low background signals.

J. Chinese Herb Med. (Zhongcaoyao) 23, 461-462 (1992). TLC of flavones on polyamide with ethyl acetate - methanol - water 6:3:1, and ethanol - water 4:1. Detection under UV 254 nm, and by spraying with 5% AlCl3 in ethanol. Quantification of total flavones after elution by photometry at 340 nm.

J. Planar Chromatogr. 5, 396-407 (1992). Review with 82 references of the advances in the techniques and applications of TLC for the separation, detection, and quantification of steroids for the past ten years, focussing mostly on industrial steroid analysis. Methods prescribed in the latest editions of the USP, BP, and Ph. Eur. are considered in particular. To differentiate between the concepts and principles of the various pharmacopoeias, the TLC methods used for identification and purity testing of steroid raw materials and formulated products are compared with special regard to the separation systems prescribed, the methods used for visualization and quantification. 1. Introduction; 2. Separation Methods (separation of pharm. important steroids on chem. bonded phases, separation of steroid epimers on chem. modified silica stationary phases, reverse phases paired ion TLC of steroids); 3. Special Techniques (separation, detection and quantification); 4. Recent Analytical Applications; 5. The role of TLC in industrial steroid analysis, with emphasis on Pharmacopoeial prescriptions.

J. Planar Chromatogr. 5, 200-204 (1992). TLC of red bell pepper extract and ß-carotene on silica with ethyl acetate - dichloromethane - hexane 24:56:20 (single development); and a variety of solvent combinations (multiple development); scanning at 450 nm (absorbance). The results show a general instability of carotenoids under conditions typically employed in TLC. Rigorous exclusion of oxygen and light would prevent the alteration of carotenoids, however, not particularly easy to achieve in practice. The use of layers impregnated with antioxidant is one possible solution. Great caution should be exercised when reviewing data TLC for the identification and quantification of carotenoids from plant material.

J. Planar Chromatogr. 5, 207-209 (1992). HPTLC of methyl paraben, p-hydroxybenzoic acid, benzoic acid and sodium benzoate on silica with chloroform - acetic acid 90:3. Densitometry by absorbance. Accuracy (expressed as % error) in the range of 0-5%, precision (expressed as % RSD) in the range of 0.5-3.62%.