J. Liq. Chrom. Rel. Technol. 27, 2019-2030 (2004). Comparison of the N-type and S-type chambers in terms of mobile phase flow rate, the Rf values obtained, and the densitometrically established concentration profiles of the test analytes. Selected were several phenyl-substituted alcohols and acids, low activity adsorbents (e. g. cellulose powder), and low-polarity solvents (n-octane and decalin) as the components of the chromatographic systems investigated. The overall conclusion from the results obtained is that the physico-chemical performance of the S-chamber is comparable with that of the N-chamber, and that the only indisputable superiority of the S-chamber is the more economical use of the mobile phase.

J. Liq. Chrom. Rel. Technol. 27, 2101-2111 (2004). HPTLC of sterigmatocystin on amino phases with toluene - acetone 20:1 followed by drying and heating at 150 °C for 15 min. Quantitative determination at 366 nm (yellowish fluorescent spots).

Indian J. Pharm. Sci. 66 (3), 283-286 (2004). TLC of lamotrigine in its tablet dosage form on silica gel with acetone - toluene - ammonia 14:6:1. Quantitative determination by absorbance measurement at 312 nm. The method was quantitatively evaluated in terms of linearity, accuracy, precision, repeatability, and specificity to prove its utility in the analysis of tablet dosage form.

Chinese J. Trad. Patent Med. (Zhongchengyao) 26 (4), Appendix 7-8 (2004). TLC of Xuanmuyi capsule extracts on silica gel with n-butanol - hydrochloric acid - water 8:2:10:1. Detection by spraying with 5 % potassium iodobismuthate. Identification by fingerprint technique. Quantification by densitometry at 510 nm. Validation of the method by investigation of its linearity range (10-50 µg/spot, r=0.9999), precision (RSD=2.1 %, n=6), standard addition recovery (100.7 %, RSD=3.8 %, n= 5).

J. Planar Chromatogr. 17, 360-364 (2004). Analytical OPLC of ascorbigen (ASC, 2-C-[(indol-3-yl)methyl]-alpha-l-threo-l-glycero-3-hexulofuranosonic acid lactone) on silica gel by means of two-step development: the first step (n-hexane) served for elimination of the total wetness front, the second (chloroform - methanol 9:1) for the separation. Detection by spraying with 10 mL Procházka’s reagent (reaction with formaldehyde), then heated for 5 min at 105 °C. Quantitative determination by densitometry at 460 nm.

Chinese J. Trad. Pat. Med. (Zhongchengyao) 27(1), 94-96 (2005). HPTLC on silica gel with 1) n-butanol - glacial acid - water 19:5:5; 2) petroleum ether (30-60 ºC) - formic acetate - formic acid 15:5:1; 3) chloroform - ethyl acetate - methanol - formic acid 200:25:50:1. Detection 1) by spraying with 0.5 % ninhydrin in ethanol; 2) under UV 365 nm; 3) by spraying with vanillin - H2SO4 solution and heating. Identification by fingerprint technique. Quantification of emodin by densitometry at 440 nm. Validation of the method by investigation of linearity (0.1 µg - 0.5 µg, r = 0.998); precision (RSD = 3.8 %, n = 15 within plate and RSD = 3.2 %, n = 5 plate to plate); reproducibility of five time assay towards the same sample (RSD = 4.4 %); standard addition recovery (99.5 %, RSD = 2.2 %, n = 5). The results for some real life samples are given.

IPC 56th 2004, Abstract No. GP-26. HPTLC of triphala, an ayurvedic formulation containing about 3.60 % of total phenolics. Separation of alcoholic triphala extracts on silica gel with n-hexane - ethyl acetate 2:1. Rf value of the main spot gallic acid was 0.04 in triphala and its formulation. The method was found to be very specific for gallic acid having a linearity range of 0.2 - 1.6 mg/mL. Several formulations analyzed by HPTLC contained 5.2 - 7.6 % of gallic acid. The reported method is suitable for estimation of gallic acid in raw material and formulations.

J. AOAC Int. 88, 1516 (2005). Short overview on the use of densitometry in thin-layer chromatography as one of the most active areas in TLC research. See also the biennial reviews of Planar Chromatography by J. Sherma in Anal. Chem 74, 2653-2662 (2002) and 76, 3251-3261 (2004).