J. Chromatogr. A 1462, 134-145 (2016). Development of simple method for the separation of different colored pigment formulations used in the printing materials on food packaging to control the quality and safety of the package. HPTLC on silica gel by automated multiple development with a 9-step gradient based on ethyl acetate, methanol and water, and ending with toluene. Good resolution of differently soluble constituents of the pigment formulation like additives and coating materials. The results obtained by multi-detection allowed a first assignment of the differently detectable bands to particular chemical substance classes, enabled the comparison of different commercially available pigment batches and revealed substantial variations in the composition of the batches. Characterization of single unknown pigment constituents by HPTLC-MS and HPTLC combined with ATR-FTIR. The new HPTLC method for routine quality control for incoming pigment batches and monitoring of internal pigment production processes secures a consistent pigment composition, resulting in consistent ink quality. Hyphenation of HPTLC with the Aliivibrio fischeri bioassay revealed information on the toxicological potential of different pigment compounds which helps guarantee consumer safety, especially in regard to readily permeable pigment components.

J. Sep. Sci. 42, 415-430 (2019). Review of the application of TLC hyphenated with mass spectrometry for the analysis of low-molecular-mass solutes. Different monolithic layers and their main applications were also described, including plates with thin inorganic layers, composite silica/organic polymer layers and porous polymeric monolithic layers (thermally initiated and prepared by photopolymerization). Methods of detection in TLC-MS systems were also described as indirect and direct mass spectrometric analyses.

Elution with ethanol - hexane 1:10. Quantitatiom by specrophotometry. Also TLC-densitometry for alpha- beta-carotene.

TLC of mononucleotides on silica with isopropanol - NH3 - water 12:8.3. Determination by spectrophotometry at 250 nm after elution.

J. Planar. Chromatogr. 1, 252-254 (1988). TLC on BaSO4-CaSO4, impregnated with coconut oil. Detection by spraying with an ethanolic solution of bromophenol blue (0.1%). Quantification by spectrophotometry 520 nm after elution. Detection limit, 400 µg (!).

Contribution to qualitative and quantitative identification.) (German). Deutsche Arzneimittel Zeitung 128, 1991-1994 (1988). TLC on silica with dichloromethane - methanol - NH3 85:14:1. Visualization with hydrogen peroxide (30%) solution, heating at 120°C for 30 min. and by spraying with acetic anhydride reagent (acetic anhydride - petrol ether - toluene 1:4:5) and heating at 120°C for 30 min. Detection limit, 0.5 - 1.0 ppm.

Anal. Chem. 61, 1911-1915 (1989). Use of pulsed laser desorption as a means to vaporize TLC spots directly into gas phase. Resonant 2-photon ionization of the resulting neutral plume of molecules entrained into a supersonic jet expansion of CO2 and transported into a time-of-flight MS. Quantification of indole-3-acetic acid and imipramine over 4 orders of magnitude by the method with detection limits in low ng range. The method is suitable for various thermally labile biological molecules, indole amines, catecholamines, peptides and drugs.

J. Liquid Chromatogr. 13, 2844-2869 (1990). TLC of phospholipids and alkaloids on silica with methanol - chloroform 7:3. Detection by fast atom bombardment MS. Increase of the effective resolution of the chromatographic resolution using MS data to trace compounds via characteristic fragment ions. Also, description of the use of a laser desorption ionization method and Fourier transform mass analysis for TLC detection. With several applications.