Chromatographia 48, 548-554 (1998). Study of double spray in TLC to enhance fluorescence of dansyl derivatives, 200-360 fold by spraying with 20% triethanolamine in propane-2, followed by 30% paraffin oil in hexane, spots are stable for one month. Visual detection limits, 1-6 p mole per spot. Use of the graphical method to explain the phenomena.

J. Planar Chromatogr. 17, 314-315 (2004). Separation of 22 amino acids on silica gel with n-propanol - water 7:3. Detection by spraying with 1) 5 % 4-hydroxyacetophenone in acetone, followed by drying in air until all solvent had completely evaporated, and heating in an oven at 110 °C for 10 min, and, after cooling, spraying with 2) 0.4 % isatin-5-sulfonic acid (sodium salt) in ethanol - water 4:1, followed by drying in air and heating for 10 min at 110 °C. Detection limits were betwen 0.1 and 2 µg.

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.