J. Planar Chromatogr. 16, 331-337 (2003). Literature recommends dipping TLC plates in viscous liquids to enhance fluorescence. Measurement of the fluorescence and absorbance spectra of pyrene spots reveals the mechanism of enhancement of plate dipping in viscous liquids - blocked contact of the fluorescent molecules with the stationary phase or other sample molecules is responsible for the enhanced fluorescence at lower concentrations. TLC and HPTLC of pyrene on silica gel and on RP-18 with methanol - acetone 8:3. The dipping solution was prepared by dissolving 3.8 g pentane sulfonic acid in 20 mL water. Densitometry in the range of 198 to 610 nm.

J. Planar Chromatogr. 25, 571-574 (2012). HPTLC of theanine in tea extracts on silica gel with n-butanol - acetone - acetic acid - water 7:7:2:4. Detection by dipping into a ninhydrin reagent for 3 s, followed by heating at 105 °C for 5-15 min. Quantitative determination by analysis of green channels of photographs using the CP Atlas 2.0 software. The hRf of theanine was 35. Linearity was in the range of 1.4-14 ng/zone. The intermediate/inter-day/intra-day precision was below 0.7 % (n=3). Recovery (by standard addition) was between 95.7 and 102.5 %.

Anal. Chem. 56, 1674-1677 (1984). Investigation of the possibilities of laser beam densitometry for thin-layer chromatograms. Picogram sensitivity appears obtainable with 15 mW power level (argon 488/514 nm or helium cadmium 442 nm laser).

GIT Suppl. Chromatogr. 3, 32-38 (1986); part II: GIT Fachz. Lab. 10, 993-998, (1986). Principle and applicability of TLC using mobile phase pressure of up to 80 bars. Circular development of single sample injected in-flow and of multi samples applied on the dry layer. Use of normal and reversed phase material, including multiple use of the same layer. Quantification of the chromatograms by direct image processing using optical sensitive RAM.

J. Chromatogr. 455, 382-390 (1988). Presentation of an indirect fluorimetric detection method for alkanols, bile acids and digoxin series for TLC on silica or chemically bonded silica with different solvent systems containing certain fluorophores, which generates uniform background fluorescence, and allowing detection of non-fluorescent spots with nanomolar detection limits. Discussion of the selection of visualization reagent and the effect of the chromatographic conditions.

J. Planar Chromatogr. 2, 323-326 (1989). Discussion of quantitative in situ scanning. Modern quantification consisting of complete on-line applications of lab computers for raw data measurements; on-line scanner optimization; complete raw data storage; statistical mathematic reduction of raw data and mathematically controlled integration and application of simple statistical mathematics in raw data treatment and in cross-correlation of reduced data. Application of these methods lead to improvements like extension of the working range of quantitative TLC by a full order of magnitude below the existing lowest quantification limit and improvement of the repeatability and accuracy of quantitative data by factors from 2 to over 6.

Part 12: Quality assessment in QTLC. J. Planar Chromatogr. 6, 62-65 (1993). Description of a program with a built-in quality assessment routine for quantitative evaluation of TLC. Together with the quantitative results, the quality of the data and the system used are also documented. Errors arising from the scanner, applicator, and chromatography, given in relative standard deviation, can be determined from the additivity of variances of these measurements.

J. Liquid Chromatogr. 19, 687-698 (1996). TLC of tryptophan, 5-hydroxytryptophan, 3-indoleacetic acid and serotonin on cellulose with chloroform - methanol - NH3 12:7:1. Quantification by in situ scanning with a fibre optic-based fluorescence instrument at 280/>347 nm. RSD, 1.70-6.52 %.