Determination of isoniazid in serum by thin-layer chromatography.) (Chinese). J. Pharm. Anal. (Yaowu Fenxi Zazhi) 17, 116-118 (1997). TLC on silica with chloroform - methanol 9:1. In situ spectra recording of isoniazid and its salicylaldehyde - and benzaldehyde-derivatives. Quantification by densitometry at 225 nm. Validation of the method by investigation of linearity and range, RSD, recovery and detection limits for the compounds.

J. Chromatogr. A 1477, 108-113 (2016). In order to study the kinetics of invertase, a specific fructofuranosidase was cloned from the Leishmania major genome. Determination of the kinetic parameters of the β-D-fructofuranosidase by TLC on silica gel impregnated with sodium bisulfate and citrate, developed successively twice with acetonitrile – water 4:1. Detection of the three carbohydrates sucrose, glucose and fructose by dipping the plates in a solution of 4-aminobenzoic acid. Quantitative determination by UV-densitometry. Description of the hydrolysis of sucrose by the Michaelis-Menten kinetic parameters (KM, Vmax) equal to 63.1 ± 7.6 mM, 0.04 ± 0.001 mM/min using glucose production and 83.0 ± 14.4 mM, 0.03 ± 0.002 mM/min monitoring fructose. Also, comparison of hydrolyses of three alternative substrates, raffinose, stachyose and inulin, and characterization of the regiospecificity of the reaction. The method proved to be suitable for the refined kinetic analysis of different reactions related to the hydrolysis of sugars.

Sz. Nyiredy, A. Kakuk (eds.): Planar Chromatography 2000, Lillafüred, Hungary, 24-26 June 2000, Res. Inst. for Med. Plants, p. 231-235. Validated HPTLC on silica gel with ethyl acetate - methanol - acetic acid 80:19:1 for ca. 15 min. Quantitation by absorbance measurement at 300 nm (polynomial regression). Recovery was found to be between 99,0 and 101,3 %, repeatability was 0,1 % for aspirin and 2,2% for salicylic acid (n=2). HPTLC method is preferred to HPLC method because of its speed (14 samples in 30 min).

1: Definitions and practice in TLC. J. Planar Chromatogr. 6, 198-203 (1993). Validation of the purity of a drug substance by quantitative TLC according to the guidelines of the Committee for Proprietary Medicinal Products (CPMP, European Community). Validation parameters were selectivity, stability, linearity, range, limit of detection and quantification, accuracy, and precision.

J. Planar Chromatogr. 14, 100-108 (2001). Test of the 'error-budget model' acc. to Eurachem/Citac Guide on measurement uncertainty using the quantitative HPTLC determination of sodium glutamate in a food product as example. The TLC procedure was divided into stages each of which was evaluated. The dominant sources of uncertainty found were sample preparation, chromatographic separation, secondary chromatography, stability of instrumentation, inhomogeneous illumination, distribution of compound molecules in the stationary phase, and the relative position of spots and scanning slit, among others. The uncertainty estimated by means of the error-budget method was less than one fifth of the value obtained from the validation study.

2: Comparison of some parameters in OPLC and TLC. J. Planar Chromatogr. 6, 256-258 (1993). Investigation of the linearity of the calibration graph, the limits of detection and quantification and the precision of the data of an OPLC purity test during the development of chromatograms at different flow rates. The best results (lowest LOD and LOQ as well as the best precision) were obtained by OPLC when eluting with the optimum linear velocity. Quantification by densitometry at 237 nm.

Proc. Intern. Symp. on Planar Separations, Planar Chromatography 2001, pp. 91-101. HPTLC of sodium glutamate on silica gel. Quantitative TLC is considered as a typical separation technique where evaluation of uncertainty can be done with seriously planned validation. The contributions of sources calculated according to guidelines are so small that their effects on the final results are negligible.

I. General principles and practical approaches. J. Planar Chromatogr. 6, 187-197 (1993). Validation of a TLC method in comparison with HPLC. Various steps necessary for the validation are: selection of the analytical performance parameters, model solutions, and stability problems. Practical guidance is also given to the performance of validation experiments. The importance is also given on the performance of validation experiments. The importance of different system suitability tests is emphasized.