GIT Fachz. Lab. 1, 14-18 (1999). TLC of hydroxybenzenes (pyrocatechol, resorcinol, phloroglucinol, hydroquinone, and pyrogallol) on conventional silica gel and specific Raman-TLC plates (coated with spherical silica gel) with toluene - methanol - acetic acid 45:16:4 in a saturated chamber. The spectra obtained by Raman spectroscopy enabled the use of data banks for the identification of substances. Typical detection limits are in the low microgram region per application.

J. Chinese Trad. & Herb. Drugs (Zhongcaoyao) 32 (4), 312-314 (2001). TLC on silica gel with chloroform - methanol - water 65:30:10. Detection by spraying with 10% sulfuric acid in ethanol and heating at 1058C for 5 min. Quantitation by spectrophotometry.

J. Planar Chromatogr. 17, 398-403 (2004). Review divided into several sections: ,Summaries’ contains a review of some recent research results in TLC-MS and PC-MS (use of a diode IR laser to desorb samples from a thin-layer chromatogram, with ionization of the desorbed gaseous molecules via a corona discharge; description of an interface between TLC and an electrospray ionization (ESI) mass spectrometer; ,on spot’ matrix-assisted laser desorption ionization (MALDI) mass spectrometry for TLC-MS); in ,Assessments and perspectives’ new results are detailed, precedent and new instrumental developments are previewed; in the section ,Interconnections’ synergies between mass spectrometry and different approaches to planar separations are explored. Finally, in ,Forecasts’ expectations and future developments, in addition to recent techniques, are described. 11 references.

Anal. Bioanal. Chem. 386, 1543-1551 (2006). Optimization of the plunger-based extraction device of Luftmann for HPTLC/MS coupling, which was originally designed for extraction on TLC aluminum foils. Some modifications enabled extraction of analytes from HPTLC/TLC glass plates. A buffering of the plunger reduced the occurrence of leakage. The involvement of a torque screwdriver for the fixation resulted in a reproducible contact pressure and avoided breaking the glass plates. HPTLC of two derivatization products, xanthylethylcarbamate (XEC) and dansylethylamide (DEA), on silica gel with acetone - n-hexane 1:4 and ethyl acetate, respectively. Quantitative determination by absorbance measurement at 233 nm (XEC) and fluorescence measurement at 366/>400 nm (DEA) before online extraction with ChromeXtractor interface connected to ESI mass spectrometer. For determination of the precisions of the extraction, selected ion monitoring in the ESI+ mode was used. For XEC the [M-NHCOOC2H5]+ signal at m/z 181 and for DEA the protonated molecule [M+H]+ at m/z 307 and the sodium adduct [M+Na]+ at m/z 329 were obtained. The overall mean repeatabilities (%RSD, n=7) were 18.6 % (XEC) and 8.7 % (DEA). The determination coefficient of the calibration function was established to be 0.9991 (XEC) and 0.9919 (DEA). The limits of detection calculated from the S/N of a 1-ng zone were 52 pg/zone (XEC) and 160 pg/zone (DEA). The employment of the interface for reduced plate thicknesses was also demonstrated. Repeatability of the extraction from glass plates, linearity of the signal obtained, and detection capability were shown to be comparable to the original device, which was only usable with aluminum foils.

Planta Med. 53, 546-548 (1987). TLC on silica with the organic layer of ternary or quaternary solvent systems. The method is applied for the selection of eluents for rotation locular counter-current chromatography (RLCC) and for the analysis of the separated fractions. Suitable solvent systems are given: chloroform - methanol - n-propanol - water 5:12:1:8; 9:12:1:8; chloroform - methanol - water 43:37:20; ethyl acetate - n-propanol - water 4:2:7; n-butanol - n-propanol - water 2:1:3.

J. Chinese Anal. Chem. (Fenxi Huaxue) 29 (4), 484-488 (2000). TLC on silica gel with a mixture of propanol, chloroform, and NH3. Identification by matrix-assisted laser desorption/ionization-time-of flight-mass spectrometry (MALDI-TOF-MS). Quantification by TLC/FID. Discussion of use of the method for the quality control of the product.

Sz. Nyiredy, A. Kakuk (eds.): Planar Chromatography 2000, Lillafüred, Hungary, 24-26 June 2000, Res. Inst. for Med. Plants, p. 121-132. A variety of modes of multidimensional separation in TLC are shown. Two-dimensional or multidimensional planar chromatography, two-dimensional development on bilayers, coupled layers with stationary phases of decreasing polarity and combination of multidimensional planar chromatographic methods are demonstrated. The greatest strength of multidimensional separation is that compounds are distributed widely over two-dimensional space of high zone capacity. A zone capacity of ca. 1500 could be achieved. Image analyzers might improve quantitation in future.

J. Chromatogr. 395, 47-53 (1987). Description of an image processing system consisting of a solid state camera, a framestore, and a computer which enables high-resolution images of the plates to be recorded and processed in a variety of ways. To correct for nonuniform illumination, the images of the developed plates are rationed with that of a blank plate. Software allows the images to be enhanced and smoothed, and automatic quantitative analysis to be carried out.