J. Liq. Chromatogr. Relat. Technol. 38, 1113-1120 (2015). HPTLC of orbifloxacin (1), danofloxacin (2), ciprofloxacin (3), norfloxacin (4), enrofloxacin (5), marbofloxacin (6), difloxacin (7) and ofloxacin (8) on silica gel with 1,4-dioxane - ammonia - tetrahydrofuran 6:3:2. Quantitative determination by absorbance measurement at 320 nm. The hRF value was 19 for (4), 23 for (3), 30 for (2), 37 for (8), 40 for (6), 44 for (5), 56 for (1) and 59 for (7). Linearity was in the range of 159-513 ng/zone for (1), 99-238 ng/zone for (2), 97-244 ng/zone for (3), 69-163 ng/zone for (4), 63-170 ng/zone for (5), 103-250 ng/zone for (6), 84-251 ng/zone for (7) and 94-260 ng/zone for (8). LOD and LOQ were 53 and 159 ng/zone for (1), 32 and 98 ng/zone for (2), 32 and 97 ng/zone for (3), 23 and 69 ng/zone for (4), 21 and 63 ng/zone for (5), 34 and 103 ng/zone for (6), 28 and 84 ng/zone for (7) and 31 and 94 ng/zone for (8), respectively. Selection of appropriate viscosity of the mobile phase may be important in obtaining optimal chromatographic separation.

J. Planar Chromatogr. 3, 521-526 (1990). HPTLC of estrone, equilin, equilenin and their 17a-diols on silica with cyclohexane - chloroform - methanol - triethylamine 16:18:2:3 and, after drying, chloroform - dioxan - triethylamine 40:3:2 (same direction). Mestranol was used as internal standard and densitometric measurement was made in the reflectance mode at 282 nm. Also study of the relationship between structure and retention.

Anal. Letters 26, 1787-1797 (1993). Reverse-phase HPTLC of three amino acid hydroxamates (arginine hydroxamate, threonine hydroxamate, histidine hydroxamate) on RP-18 silica. Study of the effect of different organic solvents as modifiers, both three solvents and four solvent systems, by using mixture design and a chromatographic response function.

Proc. 9th Internat. Symp. Instr. Chromatogr., Interlaken, April 9.-11., 311-312 (1997). Presentation and discussion of equations permitting the determination of the relationships between RM values of the substances and the composition of multicomponent mobile phases on the basis of measured chromatographic and absorption parameters and experimentally determined partition coefficients of the substance between the mobile phase components. Densitometry.

J. Planar Chromatogr. 13, 414-419 (2000). OPLC of 13 benzodiazepines (alprazolam, brotizolam, carbamazepin, temazepam, chlordiazepoxide, cinolazepam, clobazam, clonazepam, diazepam, nitrazepam, midazolam, medazepam, prazepam) on HPTLC silica gel with 8 mobile phases (benzene - chloroform - nitromethane 492:313:195; chloroform - dichloromethane - methyl ethyl ketone 809:115:76; acetonitrile - chloroform - toluene 136:651:213; chloroform - ethyl acetate 825:175; acetone - chloroform-methanol 28:876:96; chloroform - dioxane - toluene 784:154:62; acetonitrile - chloroform - tetrahydrofuran 268:840:132; acetic acid - chloroform - n-butanol 95:862:43). Detection under UV; densitometry at 240 nm. According to the results Snyder's endogeneous solvent strength (Si), proton donator (Xe), proton acceptor(Xd), and dipole(Xn) parameters are not satisfactory for complete description of a solvent mixture used as mobile phase.

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.

J. Planar Chromatogr. 25, 269-276 (2012). Important steps to reduce the systematical errors in planar chromatography were described. Different aspects such as selecting the center of the plate, repairing the unwanted start chromatography by using a solvent, avoiding mobile phase interaction that may influence hRf values, improving signal integration by multi integration at mini stepwise positioning, applying statistical methods for outlier removal and data correlation of signal over substance mass were defined as important parameters to improve repeatability standard deviation.